Stomach problems...what r they?

I'm anemic and get intestinal viruses more than normal as well but I have had this problem since I was little..I feel like its from starvation cause I do Starve myself well forget to eat or just don't feel like it then if I don't eat by the next day I get severe pain in my stomache like it's shiveling then I may vomit but I do have bad diaheria and can't move but have to force feed myself bread and it gets better then...what is it?