A few suggestions, some have helped me with the "night sweats" problem, and some I read elsewhere:
Try eliminating all sweets and all fruit for awhile from your diet. Candida or other bad bugs multiplying in your digestive tract can (possibly) cause night sweats and can also cause digestive problems, as well as food allergies - which is what you might have as you describe "react to things you eat".
If leaving out all sweets and all fruit for awhile helps, you'll at least have it down to it probably being some type of bad bug (parasite, like candida or another one). NOte that fruit is not a bad food per se, but it is bad while the person is battling a candida or problem with certain other parasites that may feed off of the sugars in fruit. Once problem with bug is gone, you may be able to eat fruit again without problems.
Next, are you regular? Do you have a bowel movement - a good one - or more than one, every day? If not, bowel cleansing is on your "to do list"! I would do the bowel cleansing before (or at the same time as) trying to kill off bad bugs like candida or others.
Read through lots of posts on the Bowel Cleansing forums to get an idea of the wide variety of products out there to help you Bowel Cleanse. There is also a Candida Forum and a parasites forum.