Bleeding after sex Can this be normal??

So I'll be 20w tomorrow and there's times where Iv bled after sex but just from hitting my cervix and not being wet enough. So we had sex today (45 minutes ago) but we didn't realize til we were done that I was bleeding. I have no clotting and no cramping and I feel babygirl moving around but I still have his bleeding and it's enoug right now to fill a pad since it's still fresh and it's red. I'm just worried. Should I wait a few hours to go in? Should I call my ob? Is this normal to have happen with such bleeding and be ok just from sex????