M.J.
I would speak to the Dr. My daughter went through the same thing. I tried all kinds of methods to try to help her start using the potty again and nothing worked. At one point I finally realized that she couldn't help it. The dr. did an ultrasound and found a blockage which was pressing on her bladder causing involuntary peeing and pooping. We did laxatives for three days (and stayed near a potty!) and then Miralax for several months to help her body get back into a routine. One thing to be aware of, my daughter was going poop in the potty daily when this started, so I had no reason to think she was constipated. She just wasn't going enough to clear out her system.
Hope you guys get through this soon. I know it's tough!