Hi and welcome to HCM!
Thanks for posting your query here.
The common cause of sore throat
is strep throat
. If immediate attention is not paid it will result in septicemia
and finally arthritis.This manifests as joint pains
. A blood work up will give you a clue to the diagnosis like elevated RA factor.Congestion of head and stuffy nose can be relieved by using decongestants.
The change in the voice still shows some remnant infection in the throat. Hence please consult a physician who will check whether it is strep associated arthritis or a simple viral arthralgia
. In the mean time you can use some analgesics to relieve the pain.
Hope this is helpful to you.