Being Stubborn

I do not buy into food fads and diet trends usually. I spend a lot of time working towards exercising every day and coupling that with attempting to eat better and with school beginning again three weeks ago, the processed foods sneak back in the diet and suddenly, I find myself getting sick after eating...often.

I do not believe I have any sort of gluten allergy, I can eat bread without any problems, but processed or sugar heavy foods... destroy me. 
For example, I made pancakes this morning and almost immediately after eating them I felt ill.  I am trying to figure out if it is a sugar thing, I do not eat a ton of sugar, but if I do eat something horribly sweet in a large quantity...it gets me ill every time and I am thinking some of these processed foods have just hidden sugar in them
It is so hard to pick and choose at the grocery store and maintain a budget so this food issue is really bugging me.
I bought a lot of fresh fruits and veggies this week... so we shall see, obviously the pancakes are doing horrible.