What Causes Delayed Menstrual Periods,sore Nipples And Enlarged Labia?

I had the depo injection but when i was due to get the second i didnt get it because id been havin constant irregular bleeds. i havnt had a period since. i was supposed to have the second at the end of november...nearly four months later i have no period, very sore nipples and an enlarged labia...it could be because my period is due, but ive never had these symptoms before?