And yes, you should call him and discuss your concerns. I would not go around him and take the pred without letting him know. I would listen to his arguments (assuming he will make any - my bet is he will just agree with you to get you off the call) and then decide whether to seek care elsewhere or work the taper directly with your GP. Since you are seeing him next week for another scope, what about
suggesting that you hold at 40 mg until then?
In my opinion it is better to be aggressive and completely kill the flare instead of trying to manage the meds so carefully. I spent probably 5 years with smoldering disease until I developed joint pain everywhere and ended up on 60 mg/day for a month. That taper took 3 months.