I've had head pain for months and now it seems to be spreading to other parts of my body.. Please help!?

In mid march I started getting head pain.. Its not like a headache but more like pain when you get a bruise. I noticed it after nodding my head back in forth to a song later that night. Ive been to several doctors including a neurologist.. Ive had an MRI and it showed nothing wrong.. Was also tested for Lymes disease and came back negative. I have also gone on pain medication and it hasnt helped.. Now recently a couple weeks ago the pain seems to have spread a little to my arms and legs.. Sometimes I even feel Nausea at night. Nothing seems to be helping me and the doctors cant find anything.. Does anyone know what is causing this? I'm only 21 years old and think I'm too young to have Multiple sclerosis and I dont think I have a parasite because so much time has ped.. Please can anyone out there help me?