I've only found 2 molts in the month that they've been in the tank. All but 1 of them laid eggs as well, not sure if that changes anything.
Two days ago I did a PCW and introduced the new, lower PH water via drip method. The PH is now hovering around 7.9, with another water change coming tomorrow that will hopefully put it closer to 7.6. I also gave the shrimp some blanched kale in hopes of helping build their exoskeleton in case it was external.
But overall, no change. Seems like more of the shrimp are showing symptoms, I may try to up the salt level and I'll keep treating with hydrogen peroxide and hope for the best.
Whatever it is, it's slow moving which may be the one highlight, but I had to see these poor little girls suffer.
Hopefully I'll round the corner at some point soon.
Thanks again for your help!