Hey funny bunny
welcome to the mad house, i'm a fellow Irish crohnie and yes the meds are pretty much the same, I was on pentasa for a long time. It worked wonders but yes there was some wind pains but it helped when I played around with when I took it and what I ate before or after, pentasa stopped working and I changed back to asacolon and again it depends on when I take it. If your crohn's has changed location or spread then pentasa may not be targeting the right area, I know a scope is not on the top of anyone's wish list but that and some other tests may help to locate any new issue's. Pentasa, asacolon, salofalk and mezavant etc are pretty much the same drug but they release at different times in the system. have a chat with your IBD nurse and see if maybe even giving one of the others a go will help. I tried mezavant earlier this year and by day 4 I felt great by day 10 I couldn't get out of the bathroom, changed back to asacolon and it all settled within a week. so you should get results and answers fairly quickly as to which works best. If that fails as the others have mentioned then there are plenty of other meds to try and in the different combinations.
Good luck and let us know how you get on.
Gwen xx