I recommend first you see your doctor. Very soon.
Second, you may need to see a chiropractor (be cautious on whom you see as many are after insurance money).
If not a chiro, a CMT (Certified Massage Therapist) may be able to assist you, I am one, but I would not see you without the doctor's consult first to be safe.
The body shifts so much in pregnancy, and the muscles move so much to accommodate that precious baby... You may have a dislocated rib, but it may just be you need to be realigned... and a massage can sometimes help. I have realigned clients with reflexology and a massage as I provide gentle stretching. But as you have something causing pain - any reputable therapist I would hope would want to hear what an MD would have to say. I'm the type to play it safe in my work.
Good luck and get yourself taken care of immediately as no one on here can truly diagnose you or advise you.