Do you still have it ? If it is WROD. The shrimp will have a new exoskeleton stuck under the old one. By forcing the shrimp open on the splitting line you can verify this.
If it's a shrimp only tank:
Nitrates: Must remain under 10ppm - consider 20 ppm as already toxic. And in reality 0 ppm would be ideal.
In opposition to fishes, You cannot "water change" problems out. Depending on "how fit is your water source" Large water changes could dangerously alter the stability of your water parameters.
If you are using lots of botanical and other mineral additive. 10-15% water change every week, with water already mineralized and balanced, is already enough changes. Monitor mineral levels and adjust water changes frequency and size accordingly.
You need a GH, KH, PH, TDS and Calcium testing kit. If you fear that your source of water has some mineral deficiency you need to know it. and address the problem before changing the water.
If you are normally on the cheap water changes like me, regular testing and mineral supplements are marvelous.
If you are using plant fertilizer, Running the water regularly over activated carbon every month prevents buildup of non-chelated iron, copper, and manganese, that are toxic to shrimps and can result in stalled or incomplete molting and reduced growth and reproduction.
The more I read about them... The more I see how "easy" they are to keep in perfectly ideal conditions.