Lower back pain due to back to back childbirths?

I got pregnant with my second child when my son was 8 weeks old. So to say my bodys been through the ringer would be an understatement. I'm wondering if I should consider sueing the doctor that delivered my children because at the end of my first pregnancy I started having pelvic pain and my pelvis would actually pop in and out of place when I'd flip over at night. I spoke with him many times about it with my first pregnancy and he kept putting it off and never really tried to help me with it. In delivery he had me push and strain for 3 hours before helping me with the pregnancy. Yes...I know that getting pregnant right away wasn't the best thing....but it just happened and I don't agree with terminating pregnancies. The whole pregnancy with my second my pelvis started off poping in and out of place at night...and again i asked him about it and still nothing was done. Again I delivered my second naturally...delivery didn't last nearly as long for her..but I'm wondering if I should have had a c-section the first time. Now I have problems doing my daily activities...and every night I have to pop my back just to be able to relax enough to fall asleep. I am considering asking for legal advice but wanted to see what people had to say on here first.