M.C.
Call the doctor! Pain that doesn't go away within a few days, that has no OBVIOUS explanation, needs to be checked out! Chances are it isn't a big issue and the doctor will cal;l you in and check it out - and tell you what is going on... but if it is something worse... waiting will only cause MORE problems. To be honest... what you have sounds a lot like mastitis... ouch! (which occurs in breastfeeding women, but I don't know if other women get it too?) But, don't take my word for it- go to a professional!
In the meantime, maybe get some cabbage leaves or take a warm shower...
Good luck!