My Friend Is 63 Years Old, Homeless, Sleeps In His

My friend is 63 years old, homeless, sleeps in his car. He came over this morning with nausea and he vomited twice. He said he vomited earlier this morning and it was white, when I saw it it was like a light brown and mushy, no lumpy stuff. He doesn't eat that well, occasionally I will feed him. He needs food I know and healthy food, but can't always afford it. He said his stomach feels harder than usual. I wonder if it is malnutrition. I don't think he is just hungry because he had an incident where he passed out while he was in the shower and was taken to the hospital and stayed for a day, in bed. He never was told or didn't ask anyone what happened or what was wrong with him. I want to give him some food, a little for now. Would cream of wheat be bad to give him? or is a fluid better? If the food doesn't help and he still feels sick, I will take him to the doctor. Or if you have any clue as to what could be the cause .