I have had a sore throat for about 9 days. i tested positive for covid 8 days ago but have since tested negative and generally feel better. still have cough and sore throat/pain when swallowing. how long will the sore throat from covid last?

Get an exam by your MD & a throat culture to be sure there is no coinfection with strep or a tonsillitis. A chest exam to exclude lung inflammation is also important. If neither, I would regard this a possible long covid. My sense is that your symptoms will resolve in another week or two as I think a prolonged throat soreness isn't a classic long covid symptom