I developed oral thrush during a covid-19 infection, was on clotrimazole, then nystatin, now fluconazole, 200mg once then 100mg/day- started to clear up at first but after a week growing back. dr says to continue another week, could it be dying off?

Do you mean the meds. dying off, or the Thrush. If you mean the medication, I would continue with the Rx. Then, you will know the result.

First, it is crucial that the diagnosis be confirmed professionally. Self diagnosis of thrush (yeast infection) is very unreliable. For example, coated white tongue usually isn't a yeast infection. If confirmred, the yeast causing it may be resistant to the azoles and nystatin, in which case you need different treatment, e.g. with an "echinocandin" drug. Discuss w/ your doc, or see ID specialist.