if it' deflating don't worry, it's just a hydrolic flush, they do that to refresh the water in their hydrostatic skeletons, it also works like taking a huge piss.. flushing wastes
Considering that leathers to begin with are excellent beginner corals, there isn't much that need to be done with them. Give them a little bit of light some iodine and some strontium/molybdenum and you should be good.
I have a number of leathers and I have only had one that stressed out and dropped the head. This one is growing back very quickly.
Don't be so easily fooled by one as a small piece of one will regenerate itself.