I have been dealing w SFN for about 8 months, and have several related autonomic symptoms along with the pain. My neurologists have concluded that the horrible constipation is part of the autonomic nerve damage. They prescribed miralax daily, and then supplement with a doculax (suppository) whenever I hit about 3-4 days without going. I find that the miralax prevents painful dry problems when I use the doculax, so the combination has been helpful for me. Sometimes, after using the suppository and continuing w miralax, I'll have a few days where I go regularly, then the whole cycle starts again. This has been working for me. Also, on days when pain is so bad that I take a narcotic pain pill, then I double up the miralax, in morning and evening, because those cause such constipation. I also try to drink a ton of water and get some form of exercise (the pool has been a good solution for me where i can get comfortable enough to do some light exercise) every day. I agree that the constipation can be worse than the pain, it's just a terrible additional problem to have on top of all the rest.