Just to chime in here again. I too am keeping pyramids and had the same mouth issue happen. I lost one of my three to the mouth issue, but have kept the other two for some time without issue.
If you treat them immediately with NFG or another general antibiotic / anti fungal med you should be fine. In my opinion, they are relatively hardy.
If you treat them immediately with NFG or another general antibiotic / anti fungal med you should be fine. In my opinion, they are relatively hardy.