Prozac/Clonazepam

I've recently started taking Prozac 20mg and have been on them for around two weeks. I saw a psychiatrist last Friday who recommended me to up the dosage to 40mg as of yesterday. Ive been fine on the 20mg but upped to 40mg and this has knocked me for six, I feel away with the fairies as they say. He also prescribed Clonazepam as a subsititude for Vallium. I didnt really want to take this but have had to today as my anxiety was quite bad this morning. Has anyone else here been on 40mg of Prozac and had these effects, do they ease off? Personally I think 40mg seems a bit much but Im just listening to what the psychiatrist says.