Sometimes you can dislocate your pelvis when pushing. Happened to my friend and cousin and they didn't know until the pain wouldn't go away. Talk to your doctor.
im not sure where ur pain is, but after i had my first i needed PT for about a month because i had trouble walking due to my hip/pelvis become weakened. i wpuld say u should see a PT or ask ur dr for recommendation b/c mine told me if left untreated sometimes it will take longer to heal or heal badly. better safe than sorry