Ocean's Breath Plateau Why can't I cross this river?

She threw a stick at him. He bregrudgingly took it between his teeth and held it there, feeling absolutely stupid about it, until she started to get to work. As soon as she cut in to the inflammed tissue his grip tightened and he was grimacing over the stick, teeth digging in.

Out came the bad stuff, on went the good stuff. She gave another warning before things got worse, and he hummed a sound against the stick (something like "get on with it" but he couldn't exactly enunciate), and braced himself for more.