I would not dismiss the chance that the Protonix is the source of your depression. I have never had a depression trouble untill my GERD started in May and I started Nexium. It worked great and I was thankful for it. But I started being depressed and having muscle and joint pain, acne and other bizzare things. I thought I was going crazy. I dug around on the net for people having Nexium side effects and found lots of people with the same problems. These are not common side effects but are possible from what I read. After my GERD decreased greatly from the Nexium I got off of it and started modifying my diet, no coffee or carbonated drinks helped the most and everything else diet wise everyone talks about
here plus I started the Vinegar and also molasses. My depression and other side effects went away after stopping the Nexium, so I would say keep digging around and asking questions Nexium and Protonix are the same type med.