Pregnancy pains.

I'm 12 weeks and my boob pain had mostly went away.. and now I'm back to can't even wear my sports bra... And I hurt from my shoulders all the way down my back and down my right leg. I'm only 12 weeks!! Why in god's name does it feel like I'm having nerve pressure pain? (Like sciatic nerve pain) I felt awesome the last few days and now I feel like hell all over again.