I'm vegan and when I eat meat or dairy I get really ill for three days. (vomiting and diarrhoea)
So this happened the other day and I called in sick at work on the second day (to give them time to find cover) to say that I wouldn't be coming in and the keyholder at the time said that was fine. I called in the next morning as we have to anyway and my manager didn't believe me and that I have to come in. I said I would literally sh*t myself if I came in and said she'd be 'having a talk with me when I'm back'.
She's been veggie for years and has never had a problem and says that I'm lying, but I tried to tell her that everyone's body is different and reacts differently. What should I do/say when I go back?

as a vegan, why are you eating meat and dairy, especially if it makes you violently sick ? you didn't mention what you do for work, but many companies require a doctor's note if you are out for multiple days at a time, maybe why she needs to have a talk with you?

It was by accident when it happened, but sometimes if I'm out and there's nothing else to eat, it's that or starving.
I work for Monsoon a clothes store, and it was just the one day I was calling in sick for, and I don't have a doctors note because 1: I'm at university and my university doctors are only open on weekdays and only book in patients for the next day (I was meant to work on Saturday so called up on the Friday and Saturday) So I wouldn't be able to get a note till Monday anyway. 2: I've had loose bowels since October since turning vegan in Auagust and the doctors have been terrible at it, not giving me any sick notes and not taking it very seriously (It's taken me till now end of March for them to decide to refer me to see someone about it :/ )

There is no need to give the full details of what your sick with or why when you call in. Simply saying "I am vomiting and have diarrhea and will not be able to make it into work today. I will call later on if I feel I won't be able to make it in tomorrow" is all your employer really needs to know. An employer has no right to know your medical history in detail. Some companies require a doctors note, but thats a different issue.

Also, I see where your boss is coming from. As someone who hasn't eaten flesh in many, many years, the few occasions I've accidentally consumed some (it happens), I felt mentally disgusted but it has never made me physically ill. I think the majority of long time veggies don't become physically ill from accidentally eating a small amount of animal products. It's kind of a strange reaction. I think I'd have to deliberately eat a whole steak or chicken breast to become physically ill from it, which wouldn't be accidentally taking a couple bites of a dish containing it unknowingly. If you did only accidentally eat a small amount and had this kind of reaction, thats probably reason to check out if you have an allergy which would allow you to get a legitimate doctors note next time for an allergic reaction.

From what I remember, you need to continue to eat meat in order to produce the correct enzyme to break down meat. I suppose it is possible for it to make someone extremely sick if their body has lost the ability to produce the proper enzymes, and if your body is in a very alkaline state, that might be harder for some people to do than others. In a sense, she probably has an enzyme deficiency which would include some of the symptoms she's talked about (gas, nausea, stomach cramps, diarrhea).

The same happens with milk as well. I was already sensitive to it, but as I cut more and more out of my diet (pre-vegan days) I found I'd get sicker and sicker afterwards. Not too long ago I ate a dish that had heavy dairy in it without my knowledge (silly me forgot to ask). I ate it then realized mid way that it was full of cream. I was sick the entire day with the same symptoms. I suppose it's the same reason people who are lactose intolerant take pills which are actually the enzyme.

No idea how nerdy that was, or if it was even interesting... but, the more you know, right?!

Back to OP, I would refrain from mentioning the specifics next time. Like Kiwi says it's only if it's consistent sick days that you really need to get a doctor's note. I know accidental is one thing, but I'd also avoid eating 'last resort' meat dishes. Maybe you could store some emergency foods in your car or something, just in case there's nothing otherwise available?

I think because I thought it was just fake meat as my friend cooked me dinner and I assumed she knew I was vegan as I've spoken about it before, but she must have forgotten. So I ate a whole curry with meat pieces. But the meal have had milk in aswell, which I also have a bad reaction with

Yeah I'll need to make sure I'm prepared whenever I go out now or at least double check as it was horrible going through that. Thanks

Blimey! I can't imagine eating a whole curry without noticing that it's full of meat. My meat subs are nothing like as convincing

I know it is a common expression for people to say they are "starving" when they haven't eaten in a few hours, but it is helpful to remember that you really aren't starving just because you are hungry. You could easily fast for an entire 24 hour day if you wanted to.

Imho, I think you need to take responsibility for what you eat. If you are vegan, then you need to tell people when they invite you for dinner, every time. (And it's nice when you bring something vegan to share.) And you need to keep some food around for when there are times vegan food is hard to find. Keep some nuts, vegan bars, fruit, pb & js - whatever you like in your backpack or car so that you don't have to eat something that is going to make you violently ill and go against your beliefs. You're at university. I imagine you can manage to keep yourself fed properly.

Be careful of the alcohol, it lowers inhibitions. I read recently that some veg*ns eat meat when they are inebriated.