What Causes Ineffectivness Of Hydrocodone To Reduce The Pain From Croh's Disease?

hi, my boyfriend has crohn's disease and he recently went to the ER and the doctor prescribed him some hydrocodone 5mg/325mg. At first, he was only taking one at a time, now he's taking two and they are still not working for his pain. He can't stand for more than 5 minutes and I just want to know if there is anything else that he can take that might help and what else should we do if there is anything we can?