I use diazepam but that's for more general anxiety. Haven't noticed it affecting my shy bowel. Also benzos are highly addictive so you can't use them too often.
Not tried beta blockers so don't know about them.
On the crohn's front: I have a neigbour up the road who had bad crohn's. He lost a lot of weight. They operated on him to remove a bit of his colon but there complications. He went back to Tunisia to rest, and his mother gave him a drink every day for three months. It was made from ground fenugreek seeds (1-2 teaspoons) in water. After three months he came back and the doctor couldn't believe how much he'd recovered.
Just passing that on in case it's any help. Difficult to know how much the recovery was due to the fenugreek and how much due to the surgery.
(Am trying it myself for my IBS at the moment but taking a break over Christmas. Though not sure how effective it will be for IBS.)
Your English is very good by the way.