painful sex after first child

Okay so ever since I had my daughter back in October 2015  it's been painful to have sex. It's just very uncomfortably and it feels like he's too far in there (when this was never a problem before). I can only really do it in certain positions and slow.  I don't understand bc I've never had this problem before. I went to the doctor and they told me I didn't have any infections so I'm wondering if this happened to anyone.  I'm currently pregnant with my second child so im hoping I can find something to help me soon.