I Am Trying To Figure Out What Is Wrong With

I am trying to figure out what is wrong with my husband. Since March of this year, he has been having dizziness which affects his balance sometimes, no energy, diarrhea and sometimes will vomit usually in the morning when he first gets up. it doesnt seem to make a difference what he eats, he will have diaarrhea every day and the dizziness-lightheadness. He had been to a gastenlogist and neurologist and they couldnt find any thing wrong with him. he has had a colonscopy and there wasnt nothing wrong there either. our primary physician is baffled. He has been on medical leave since March. He has graves disease and takes sythroid, type 2 diabetic and takes metformin. he watches what he needs. his blood sugar and t4 count is within normal ranges, Please help determine the cause of this. He has never been sick like this berfore