HI, WELCOME TO FISHLORE!
The first thing I noticed is that your nitrates are at 20....shrimp need cleaner water than this. To maintain the tank it should have lots of small changes, say 25% every day until it gets down to between 5 & 10....THEN when you do changes it won't be such a shock.
Remember you can't use many medications, and nothing containing copper with shrimp.... To be sure there are no problems with metals in your water you are filling the tank with, try using Prime as a conditioner. Good Luck