weird pain

Amy
I go to the doctor tomorrow for my 32 week appointment but I thought I would ask. This evening I have had a weird cramping pain in the muscle tissue behind my right boob. It started around 6:30 and has been coming and going ever since. With it, I was having sweats and taking deep breaths made it worse. Any thoughts? 
I have thought.....
Maybe my bra was too tight (took it off) 
Maybe I didn't drink or eat enough (we had dinner and I have been drinking water like crazy) 
I got my T-dap/whooping cough vaccine today (maybe it's a reaction) 
Thanks for any of your thoughts.