Painful sex (postpartum)

I have a high sex drive and this is killing me.. weve always had a super active satisfying sex life but now I'm either too afraid of the pain even though it doesnt happen all the time or I just cant handle the pain.. we were cleared by my ob to have sex and everything should've been fine, but sometimes it's just an awful pain no matter how lubricated this are or how bad I want it to happen. It hurts the worst in doggy position and I have never hurt that way before, almost feels like he is just ramming into my cervix (he isn't) it happens in other positions but doesnt hurt as bad or happen as often. Last night was by far the worst, it hurt so bad halfway through I just lost all interest in finishing. He was really gentle but still hurt like hell and I had a cramping feeling for a couple hours after.. has anybody else had this happen or know what could be possibly causing this?