I gag when I drink water but nothing else. Then again I hate the tast of our water. Taste all irony and nasty but force myself to drink it. But I do agree with gredslori.
Are you eating foods that you like? You may have an overactive gag reflex which can cause this to happen. Sometimes just thinking about gagging, the gag reflex will kick in and you will gag. Try not to put food too far back into your mouth and see if that helps and always chew your food really well so that you are not trying to swallow food that is too big.