Very unusual behavior, why is she doing this?

[Moofins07]

Most indications still point to an RI. Mostly the excessive yawning. As for the "screaming" noise, you have me stumped. My best guess is this IS some form of wheezing, even though it doesn't seem like it. The snake could be sucking in air, trying to breathe, when it yawns, causing this high-pitched wheezing.

However, with an RI, by the time you DO hear popping and see the bubbles/mucus, that means it's quite advanced. The BP could still have an RI, just in the beginning stages. That would explain why she's refusing food. We don't feel much like eating when we're sick, either.

I would suggest bumping up the ambient and the warm spot temperatures by a few degrees. Have the ambient temp at a minimum of 80, and aim for a warm spot of 90-92. Low temps can cause an RI. People say to not go any lower than 75 degrees, but that doesn't mean it's a suitable permanent living temperature.

I also didn't see an info on the humidity. If it's too low, that can cause an RI on its own. My best suggestion is to have your friend fix the temps right away (and maybe the humidity) and make a vet appointment. If it's there, catch it before it gets bad. You can never be too sure.

Good luck!