I have had this for 4 years now... I feel your pain... literally, every day, after every meal... feels like you're being jabbed with a knife..
Things that have helped me are:
1) Vegan diet - with ample raw veggies, soaked and cooked grains, legumes, healthy oils (coconut oil)
2) L-glutamine to help heal the gut holes
3) Some form of strong probiotic to help aid digestion
Likely you are going to feel like this throughout the taper, because pharma drugs are notorious for screwing up digestion... so no worries, you will heal from it... but I would do your best to manage until you're off.