... have never suffered any side effects with the injection. Now, all of a sudden and one month before my next injection is due, my breasts have become swollen and very sore. Everyone says I might be pregnant... but how could I be? I don't have periods. I am sure I am not pregnant -so could this be early menopause? It os making me feel really depressed as my breasts hurt when I wake up and are really sore when I go running. Could it just be that I am having side effects for the first time ever? Can someone give me a clue what's going on with my boobs? There is no other weight gain