I just put my pit on Prozac. She is overly sensitive and OCD--light chasing. She started pooping on the floor at night--probably due to fear. Since I've had her on Prozac--minimal dose- she has only pooped once and that was when there was company. I imagine that she went to jump on the couch and found it occupied--Scary!
It worked very quickly and I can see that it gives her relief. She now jumps up on the bed in the a.m. for belly rubs and cuddles with a big pit grin and a waggy tail. Before she was tentative and would just crawl under the covers and curl into a tight ball as close to me as possible.
Try the Prozac for Zelda and see if it eases her enough to work on behavior modification for the S.A.