You might be allergic or sensitive to one or more of the ingredients. I have eaten gluten foods my whole life and about 2 1/2 years ago I started waking up in the early morning hours (like midnight or 1 am) and felt like I needed to throw up, but nothing was in my stomach for hours. I went through the motions of throwing up, but only saliva and a bit of stomach acid came up and I felt better after that. This went on for the next week or so. Then one day I was watching my grandson at my daughter's house. Not much to eat in the house, so I had some toast for breakfast, a peanut butter sandwich for lunch and burrito for dinner. The next day I watched him again and had toast, cream of wheat and a PB&J. That night I threw up a lot! I made the connection that I was allergic or sensitive to gluten and gave it up and haven't had an issue of throwing up or feeling nauseous since. So many people have gluten sensitives these days.
Other people are allergic to soy, and now pea protein is the thing turning up in all kinds of vegan products. Since these things tend to be concentrated foods, I think we overdo the food and it's not something to eat at all or very often.
If you have ever eaten Beyond Burgers, it too is pea protein. Did you have a problem eating it? Sometimes things build up in your system before you feel bad, as was the case with me and the gluten foods. You must be a detective and write down things you eat and keep track so you can figure it out, because most doctors never even ask what you eat. It could be something in the Vega protein and if you were to eat a food that contained one of those ingredients, you may or may not get sick. Such as eat peas in their nature state might be fine, but eating the concentrated protein could be your body cannot handle the excess amounts. And why do you need the excess protein in a powdered drink anyhow? Eat a healthy veg diet and your protein needs are more than met. People are too obsessed with protein.