I know nothing about this but I found an earlier post and it may not fully relate to you but perhaps it will help...the credit for this post goes to JadedSweetheart:
Please, please, get to the ER. Any doctor will know that withdrawls are the worst thing for a pregnancy and it would be downright malpractice for them to NOT help you through this. As someone else said, even the jump down from 100mcg to 50mcg is not completely safe. I had to go on half meds for a weekend due to terrible pharmacies in my area and it was a long and terrible weekend.
I don't want to scare you, but withdrawls can cause miscarriage or at 22 weeks, still birth. The pain and the overall havoc they wreak on your body do affect the baby. Please don't worry about medication in the hospital causing a miscarriage, they will at least give you some sort of opiate, even if it's methadone, to help you get through while they attempt to contact your doctor.
Benadryl is safe in pregnancy (although they say to ask a doctor). I don't know about immodium. The thing is, whether or not those meds are harmful means nothing compared to going CT off fentanyl 100mcg while pregnant. Really, I can't think of much that could be worse for you.
Please, please, get to the ER, even if you have to bring the kids with you. As I told you in PM, they had to help me once when I didn't think they would at all.
Please also keep us informed as to how you are doing, even if you choose not to go to the ER, although I really feel that you should no matter what.
Good Luck,
Larry
http://www.medhelp.org/forums/Pain-Management/show/53
I sent you the link to the Pain Management forum. Copy and paste your thread. We are more than happy to help you but there are people on that forum who have been in your shoes.