Re: stomachache/headache after eating
You should start making a list of everything you ate before your symptoms kicked in. An ingredient could be triggering these side effects and maybe you have an allergy to something.
Some of your symptoms are similar to many of the things I experienced before finding out I had Celiacs/Gluten Intolerance.. which is an allergy to wheat. The most common symptoms I had were: a seemingly constant headache, stomachache or stomache just "didn't feel right," was in a daze/cloudy-minded, run down, fatigued, pale, moody, problems going to the bathroom, nausea, and stomach cramps.
If it's not a food allergy than it could be what you're eating.. like sugary and greasy foods are naturally unhealthy and could be upsetting your body. If you're prone to migranes, then anything with caffine could trigger a headache, like chocolate or coffee.
Definitely make a list of what you've eaten once these side effects start up and maybe you and/or your doctor can pin point what's setting it off.