You have two changes at once here. You cannot attribute anything until one of them moves.

Half of what people describe as tolerance is a change in the underlying condition, and the two need different answers.

Is it normal to feel worse before better? Nobody told me that.

Worth asking what specifically was measured. Pain scores move with mood and function does not.

Reference ranges differ between labs, so comparing two reports is close to meaningless. How long have you been on oxycodone?

Daylight, no flash. Not on a reagent test but the pattern is familiar.