I'm 28yrs old and I have been on the shot (depo) and I was suppose to have my shot on 0ct 1,12 but was unable to get it.Usually get my period around the same time that my shot is due, but it didn't come. Well about 2-3wks into the month my breast and nipples began to get sore and swollen, usually this never happens when my period is coming. My nipples are still sore but my breast the swollen has gone and it is already Nov 4,12. What could it be. Please help me!!!!