No, they shouldn't be acting like that. Do another wc to take the salt out, seems like they're not taking to the salt well. Never had that happen to me when adding salt. You might have to go another route, did you reduce the salt dosage to 50%?
You can probably stay the route your going it works but takes time and in many cases it will look like it's getting worse before it gets better. It is just the ich cysts maturing. In my experience with ich... I hit it with meds. Something with formalin and malachite green.