I have had hives for several years now and no one can give me a diagnosis. what could it be? im not allergic to any foods

It's a hard one: Unfortunately, the cause of hives often cannot be found. Simple things like exposure to cold air may trigger that. I've heard of case of hives caused by thyroid dysfunction. I personally believe there may be a hormonal problem that is causing that, but what hormone is doing that is hard to tell. Sometimes empiric treatment may be attempted to find a reliever. I truly sympathize your frustration.

Autoimmune Urticaria: About 50% of chronic hives are caused by autoimmune antibodies. No cure. But use high dose antihistamines to prevent hives.