Well, at least we know the frogs aren't the culprit! I couldn't imagine little Frogger in attack mode!
From what I've read, Ghost Shrimp *can* be on the aggressive side toward their own kind - especially when kept in too small of a space. I think that the recommendation is 1 per gallon, but I've also read that in a smaller area, you should keep less. . . I know that all shrimp are sensitive to flux in parameters, but I thought you had that all under control? I'm not sure how long you've had your shrimp, but they're really sensitive to copper, which can come through the water in old pipes - you can get a copper kit from API for around $7, but I'm betting you had too many and they're turning on each-other. Maybe try watching for a long period of time when they can't see you to check for aggression? Depending on your water hardness, I think it may be difficult to keep shrimp, too (MY water is very nice for frogs, which means too soft for shrimp). I'm not sure if you know what your water hardness is (Gh/Kh), but you might be able to get this information from your water company. . .
I've never kept shrimp, but have been looking into the possibility. . . maybe someone who knows more can give you more advice. . . I'm sorry you're dealing with this - hope something in here helps!