Go to the feed store, pick up a tube of 1.87% ivermectin ONLY horse deworming paste. It is around $5. Give an UNCOOKED grain of rice sized dose per rat once per day for 2 weeks. It works well on external parasites as well as internal parasites if you have never had a fecal on them.

Some of mine liked it when we had tropical rat mites here, and some put up a big ol' hissy. I just put the dose on my finger, restrain rat, and shove my finger against the side of their mouth so they have to clean it off. Works well and will get rid of the lice easily.

Please don't use the PAM. Maybe on the carpet around the cages so as to prevent the spread of the lice, but not in their cages. They would ingest it somehow. You can always use Kitten Revolution(selemectin) and it lasts a month, but I prefer to use the ivomec as the selemectin sometimes has mixed results.

Good luck, and maybe consider giving the tranquil ones a bath in some Dawn/Palmolive.