Odd happenings on Roxicodone

[QueQuible]

SWIMs girlfriend and he have been doing Roxicodone (M30s or A215s) for the past year and somewhat frequently as of last two months. SWIM and her do one each and never more of 30mg to do lines, and just go on for crazy hours of fantastic sex but it seems that sometimes, especially as of lately, swims girl has to stop about an hour or two in for unbearable itching, she is constantly in pain scratching saying theres nothing to do to fix it except lie down, scratch intensley and cry which doesnt seem good. They have tried different brands and get the same results, even taking 2 pills of benadryl prior to use and sa of yesterday does not help too much, she can be down from 5-45 minutes of just itching. What reason would this have to happen? They have been taking the same amount for the past year, doing them more frequent as of late but never doing more, the only other difference is it seems les potent, possibly because of the frequency. Halp them?