Glad to hear she's better (and I love her name)! I was going to agree that it looks like substrate - a few weeks ago, my Tonks got a mouthful of substrate when she struck the heat signature on the floor of her tank instead of her mouse. Poor girl had so much gunk in her mouth she couldn't close it and was visibly stressed, like a whole tablespoon's worth and she's only 160g. I had to hold her head and push as much of it out as possible. Not fun for either of us, let me assure you, but I couldn't leave her like that! She was fine though, and ate when I offered her the mouse about an hour later... she's my best eater, better even than my bullsnake, she's always hungry and never refuses a meal.
I would definitely suggest working with Pandora on her headshy-ness, in case of future need. I know BPs are naturally headshy, but I try and rub Tonks and Ana Gwyn's heads every time I have them out, on top and under their chins, and it definitely helps. Ana Gwyn has never been very headshy and *almost* seems to enjoy the head rubs, but Tonks really hated her head being touched when I first got her. So I was glad I'd been working on it when I needed to hold her head still - she still hated it, but it wasn't as bad as it could have been.