Back pain

I have had back problems my whole life due to a leg length discrepancy. The last few years life has been so much less painful since getting leg lengthening surgery. My pregnancy didn't even give me back pain. But now that I'm breastfeeding, I'm getting so much Middle and upper back pain in the same places that I always used to. I used to get sick from it. The nerves located in the painful part of my back are the ones that run to my digestive system. So it makes my brain think I'm nauseous. I know it sounds strange. I've felt ill twice before from this, but last night was the worst. I couldn't hold my daughter to feed her and was up all night and vomited this morning. I don't think it helps matters that my tummy is saggy now and my organs are still feeling out of place at 6w pp. what can I do to improve the way I hold her so that I don't have to suffer and can take care of her better when she needs to feed and be held? I already use a boppy pillow and a contoured back pillow when I'm feeding her. I use the cradle hold. I tried side lying last night which helped. But I was so tired I was paranoid about falling asleep and smashing her, so I don't want to risk it really. Any advice from moms who get back pain from breastfeeding?