Hi K.. I know you said you don't have insurance to go to the doctor, but the first thought I had was that she might have Celiac Disease. Its where your body reacts to gluten (the protein found in wheat, barley, and rye) and begins to eat away at the villi lining the intestines. Over time, it can be very destructive to all systems in your body. I have Celiac and what you described was exactly what I experienced as a young child.
Since you don't have insurance, in the meantime, you could try giving her probiotics (acidophilus, bifidus, etc.) every day. Remove the common allergens (corn, egg, dairy, wheat, nuts, soy, shellfish, I'm missing a few here) from her diet for 1 month and then reintroduce them 1 by 1 to see if there is a reaction. You could also try having her take digestive enzymes with each meal to see if that helps.
In the end, you will probably want to get things checked out since it could be any number of things. Good luck to you!