i know how frightening it is to eat when you don't know if its going to make you sick or not - i remember feeling sooo scared, when i was in school, to eat anything- even things that i thought were 'safe' sometimes caused me problems, and because i didn't know if what i thought was ok, would actually have me doubled up in pain ten minutes later, i'd wait and wait and wait to eat, until i felt so awful that i had to have something. by then my stomach wouldn't be ready for food, and so it'd hurt..... and the more stressed i got, the more my stomach hurted. its a big vicious cycle. i empathise.
if you haven't already started to, i think you could maybe think about doing the following:
- finding a really good GI doctor to help you work out your digestive problems- you might have some food intollerances that aren't being adressed, so there might be foods that are causing you trouble, but there could also be others that you're avoiding, that might actually be ok for you. if you can't have wheat, for example, do you replace it with something else? there are rice and maize and other non-wheat pastas and breads around- its dangerous to just cut out a big chunk of a food group without filling the gap with similar nutrients, ya know? also, you could have IBS, or something similar, in which case a specialist would be really helpful- they have loads of excellent things up their sleeves to settle tummies, to stop bloating and spasms, and to help you get all your nutrients etc, and they can help you do things like a food diary to weed out the likely culprits.
-finding a good nutritionist, to help you work out what you can eat, and how much of it you should eat, and how to fill the gaps in your diet. being seriously underwieght just isn't a great idea. you're probably low on vitamins and minerals, and if you're not giving your body enough fuel, that'll not help your emotional state either.
- finding a professional eating-disorder-specialist coucellor to talk to, to work around your food based fears and how food and control is affecting you emotionally in general. you might not have annorexia, but your eating does apear to be causing you lots of problems, so it'd be good to try and fix them.
you can totally beat this! i did- now i've got loads of cupboards full of different things to eat, a really great diet, with the flexibility and skills to find something when i choose to eat out, and the confidence to take something with me if i need to. and i can eat without fear of tummy aches now too - nowadays its a rare day that i do get a problem- and when i do, i just go with it, and cope without a panic- i remind myself that everyone has random tummy troubles sometimes... and that tomorrow is a new day.