12 year old son still not walking after 6 weeks

Hello all. My 12 year old son had abdominal hernia surgery 6 weeks ago to repair two hernias. One was tiny, but the other was the size of a quarter. Both were sutured closed. After surgery, he was walking a bit albeit hunched over and on tiptoes. Since then, he has regressed to sitting 95% of the time. He cannot lift his legs or walk more than 3 steps in incredible pain. The doctors are baffled, and we have been to pain management with no luck. It hurts me to see him this way. He says it feels as though he is ripping at the incision site. Any help, advice, personal experience stories would be helpful. Thank you!