Hi, I have been in salt water for 10 years and I can't say I'm an expert. My tang died last week and took most of the tank with it somehow. The shrimp should be fine. What kind of stress? Is the fish getting skinny? They like to eat veggies. Get some algae. First get to your local store and get some medication. I'm sure the shop person can help you to get the right one. Don't introduce anything for a few weeks. Some people have quarantine tanks, I do not so to me I check the tanks parameters, like you did, medicate follow directions and see what happens. I don't know if this was helpful, but I hear you. Good luck.
Bill