Why Doesn't My Anti Depressant Work Anymore ? Was On

Why doesn't my anti depressant work anymore ? Was on prozac for 10yrs & felt GREAT !! Then it started to wax & Wayne... Dr increased from 10 mg to 20mg. But I experienced no help with depression & the increase made me clenched & jumpy. Then zerzone...no better. I misswhen I started prozac. Within a few days I felt like the world had color again !! I could sleep ! I could eat ! I saw life for the first time !! & it was GREAT !!