I've had this happen in the past. I actually discovered that I had anxiety through steroids. My doctor said the juice probably brought to the surface what was always there laying dormant and would have popped up eventually or I never really noticed until then.
I've found in the past that dbol had been the culprit for on cycle anxiety more so than others. Some on this board have theorized that it's because of the "up and downs" of the drug when compared to test e which is more steady. If this idea is correct, it could be the short acting esters in the Sustanon (sust) that are causing the problem.
All I know is now I can do everything without any attacks anymore. I am also on medication (Paxil, and xannax if needed, but almost never needed) so i'm sure this helps. We'll see how I do when I add tren to my next cycle.