Normally I wouldn't be too concerned about reexposure to parasites, but that's if you have a healthy thriving snake. It sounds like your snake it not. With possible weight loss and lack of muscle tone, I would strongly urge you to consider a trip to the vet. Maybe take your snake's next bm to the vet for a check, but I wouldn't just assume that your snake will bounce back. You need to make some changes in order to see changes in your snake. If you're unsure of what's wrong, then that's exactly why you should see a specialized herp vet.