Dermovate - does it work??

Hi all I was diagnosed with psoriasis at the start of September. I was referred to a dermatologist and prescribed with a course of dermovate (Clobetasol propionate) which I've been told to apply liberally in the affected areas (basically, all around my groin). I've now been using it for nine weeks and it's had no effect (if anything things are worse, and it's spread more). It seems to be pretty strong and my dermatologist has reviewed me, is convinced this will work and wants me to keep going for another month. Does anyone else have any experience of this ointment and know anything about how long it takes to work? I've always had been sensitive skin and I'm worried this is just too strong and it's irritating me more! Does anyone also have any experience of Eumovate which I've also heard about? I'm very new to this, so any advice/ experiences gratefully received! Thanks Sam