Hi R.
I had a similar problem after I had my daughter. I had a lot of stitching, and it was painful for a period of time. But other things to consider (for me at least) were that 1) we weren't having sex very often, and hadn't been for a long period of time, so every time was not necessarily like the first time, but did require some extra pushing (sorry to be graphic) to get it completed, and also 2) my mind was always preoccupied with our daughter, mostly thinking she might wake up, etc., and so I wasn't ever relaxed enough (physically and mentally). Also, the fact is that I didnt feel very sexy, with something going into where she came out of:)
If none of these are the case for you, a call to the doctor wouldnt hurt, but for me, it was more psychological than anything else.
Hope that helps!
A.