Just because she brought the boa in 6 months ago, and the python is still alive, doesn't mean that the boa definitely isn't carrying inclusion bodies...

As discussed in the other thread, casual handling is NOT considered sufficient for the spread of IBD. Moreoever, it is not airborne and can only be transmitted through contact with bodily fluids. It is possible that this keeper's sanitation practices are not what they should be and it took a while for the snake to contract it.

This is, of course, assuming that the boa is carrying IBD, which is not very common despite the hot talk about it on the internet.

There could have been a temperature spike in the cage - I've seen burned ball pythons act in the same way in the past after being exposed to very high temperatures for even short periods of time.

The snake could also have some kind of systemic infection that is causing it to have neurological problems.

And also, what is up with the flies in and around the cage? One landed on your arm and you didn't appear even phased by it? Is it normal to have that many flies in your house? Or is it limited to your reptile cages?