Hello Rowan,
Your post caught my eye as I have struggled with same thought this afternoon. Currently I am taking Wellbutrin, and soon to start Zoloft. I felt fantastic this morning, this afternoon at the mall with my daughter I felt like I wanted to crawl out of my skin and my anxiety was reaching new levels. I was very discouraged, once you feel good again, the bad is so much worse.
I remind myself of what our pastor says, "Change is an process, not an event." It's so frusturating I know- just wanted to let you know I understand :)