Lower Stomach Pain During Sex, No Periods After Being Off Depo Shots, Constipation. No STD. Advice

hi so ive been having lower stomach pain during sex, usually doggy style,hurts so bad we have to stop,this just recently started ive been w my partner a year now, at first I thought something inside just tilted but a few weeks later still painful,im only 33 never had any children,form of birth control usually depo shot,ive been off shot for few months and still no period, the shot made me also not get a period,just trying to give as much info as possible,weve been tested its not an std,i do have trouble w constipation regularly not sure if this has any effect,i just know the pain isn t normal usually goes away 20min after we stop