Is Pregnancy Possible Despite Taking Birth Control Shot?

hi i was wondering could i be pregnant if im on the birth control shot i got on it at the end of april and me and my boyfriend had unpretected sex about 11 times. and i have been going though some things lately like cramps in my lower stomach part. and i be geting dizzy and weak , and sleep alot more, and the biggest thing is one day i went to the bathroom and i wipe and pink stuff was on the tissue and later on when i went to the bathroom it had turned brown and since that brown spotting be in my panties when i go to the bath room. could i be pregnant even though im on the birth control shot. and if im am since it june should i pay attention to any sighs