Yes, this sounds very OCD.Many times children can suppress very while at school and then it all comes pouring out once in the safety of their home.
Obsession is the words she is obsessing over that she hears or worries about in her brain. OCD is NOT rational. The compulsive part is the need to say, do or "whatever" it is she is doing about the words--confessing etc. The compulsion relieves the obsession-- that's where the anxiety relief comes in. Or perhaps, "fears" that you are speaking to. It doesn't make sense to them or to others but it is the cycle of OCD.
The obsessions themselves are not the problem in behavior per se, it is the compulsions (their reaction to the obession to relieve the stress and anxiety to whatever it is) that usually cause the problems, The compulsive behaviors are usally the "oddity" of OCD. Again, it is not rational.
Hope that makes sense! It is unfortunate that your Peds would not order high dose Azithromycin until you can get to PANDAS specialist. That might make a big difference. Or, have you tried routine Motrin 2-3 times a day?
This is so sudden onset following Strep, right? I don't know how they could not call it anything else but PANDAS.
Hope you get naswers and treatment next week.