Diane, I wish I had knowledgeable expertise to offer you. So far, I've not had any knee issues, so I don't know much about them at all. I read up on Baker's Cysts after you posted this....the information that Jo linked to, plus a couple of basic medical websites for us laypeople. I gather these things are generally normal and unremarkable...except when they decide to cause a lot of pain. I gather that surgery is not a terribly viable option. I gather that they tend to be self-limiting....I think that means they come; they go; they come; they go. And for you...they come.
My reading also suggests that treatment is the usual mantra....rest, and OTC pain meds, plus icing and elevation. You mention sitting at your daughter's dance competition as a suspected cause of this flare-up, but if resting the knee is good, then I don't see how this aggravated the condition.
I'm therefore wondering if you are simply doing too much in general. I know you're back at work full-time. And still doing PT, yes? At nine weeks, that's a pretty full plate all by itself. Are you also doing housework? Shopping? Errands, etc? Much stair-climbing? Do you have to deal with inclines? At the same time, you've been cutting down your pain meds. Perhaps this is why you didn't feel any pain from the cyst after surgery....until the point where you've cut back enough to be aware of the pain again.
Conclusions? Take it easy on activity, and try an effective dose of tylenol during the day (or the BS cocktail so you get some anti-inflammatories too). It sounds like this is a condition you have to contend with on and off. When the inflammation dies down, you can cut back on your meds again and see how it goes. A consultation with your Sports Med doc may offer you other insights into how to effectively manage this. It sounds like you have to learn how to balance getting enough activity without getting too much activity.
Also keep in mind that you are very early in the THR recovery process. There are so many new adjustments that your body is making to the new hip joint....these may very well be impacting stresses elsewhere. In two months, four months, six months, a year....the Baker's Cyst may be a non-issue entirely. Wouldn't that be loverly!! (I heard someone singing that song last week, and now it's stuck in my head.
Does this help at all?
Sharon