What Causes Bloated Stomach, Frequent Burping, Shoulder And Back Pain Postpartum?

i'm 5 months postpartum and still have an extremely swollen stomach to the point i'm still being asked about my pregnancy :( i'm also having some other odd symptoms like frequent burping, shoulder/shoulder blade pain, indegestion, and most recent lower back pain what could be going on? a lil history i recieved the depo shot may 19th 2010 and then had a tubal ligation july 20th 2010 if that can help in anyway.