I understand. Hopefully someone will come along that may have some information for you.
My best suggestion is to keep your eye on things...the fish, your water parameters, keep up with your regular water changes. Make sure the fish eats well, doesn't get constipated or bloated, clear eyes and overall just looks good then I wouldn't worry too much just yet. No signs of red streaks and the gills and scales all look good, try to relax a bit
I think you'll know if something is really wrong with your fish.
Don't some other fish get this when they get pregnant? Thats what I thought it is, but I wanted to get some info from other people. I don't think that there is anything at all wrong with the fish, but I am not a rainbow shark specialist... I know more about crayfish