Albinos are all CB. While it's not out of the question as it could have picked it up from a tankmate all your polys are most likely CB. So probably not a parasite but better to be safe then sorry.
Just read the last few pages. I wouldnt go nuts trying to find soft pellets. The epsom salt is a go to product for allot of us. Sometimes polys get backed up and trapped air. The epsom salt act as a laxative and can be added directly to the tank. When soaked into pellets it can also help with internal parasites.