Every doctor I go to swears Im fine and I don't have the funds to keep going!?

What do I do? If I just continue to sit in pain I am going to lose my mind. I have more then one problem. I have been getting these out of control headaches for years now, and all I have ever heard is: Try this pill and try all three of these pills together. Well the headache pain went away for a while. Now its back along with nausea and one of two things happening after I eat...throwing up or having to use the bathroom. Also I have body pain like no other and I am breaking out like crazy...also I have an obsession with my mouth being clean and I always look at my teeth and for some reason beyond me I am seeing cavities. And now my throat is killing me and it doesn't feel like a simple sore throat. Why is my body falling apart and why are all these doctors telling me Im fine. In fact One doctor straight out told me she didn't know, and another told me i was fine but I should look into getting an MRI on my head. Also I am short of cash so I cant keep going on like this. I am currently in a lot of pain and my trust in doctors is long gone.