What can I do

Ok so me and my boyfriend have GREAT SEX. Lol and almost every time we get done I get some painful cramps and it goes on for a couple days...he does have a large penis and I have been told when I had my last baby that i have a small birth canal...is there anything your guys think i can do to help ease the pain or make it more comfortable for me I mean don’t get me wrong I know I’m not the only woman that loves rough sex sometimes and to please their man at the same time I just don’t wanna mess myself up or possibility ruin my chances of having a baby