If the PR's meds include any neuroleptics (antipsychotics) then that is probably why. D2 antagonists are notorious for causing akathisia, which is akin to extremely severe restless legs, only it affects everywhere, mainly limbs and torso. Mirtazepine is another drug that can cause it (a tetracyclic antidepressant). Fucking awful doesn't even begin to describe it. I once got put on mirtazepine as a sleep aid when I got banged up and took a fraction of a tablet at first to see how it effected me. Luckily I didn't take a whole one, because even at 1/4 of the lowest dose it was bad enough I could have thrown myself out of a window to make that stop, if only there had been one, I'd have had a hard time not doing it.
One of the worst experiences of my entire life. Hell boiled in piss sounds about right. Hell, boiled in piss, thats crawled through a broken sewer in hell on a hot summer day, gotten covered in foetid demon-excrement and crawled back up the devil's own arse before being shat out into the snout of a LEO in a chunky, liquid stream of putrescent hell-diarrhea. Only with far fewer redeeming features.