I hope you feel better soon, and find out what's going on.
But with the white patches you describe, that could be strep throat or F throat.
You've been sick now for 20 days, IMO, it's time to insist the doctor looks at you again, and if not, go to the hospital or local Clinic.
Centor said clinicians should expand their diagnostic process for adolescents and young adults with sore throat to consider F. necrophorum, especially if the sore throat does not improve within three to five days. Centor said physicians need to be aware of the red flags that might indicate Lemierre syndrome, including unilateral neck swelling, rigors, night sweats or high fevers. There is not a routine test for F. necrophorum pharyngitis and a CT scan is required to detect Lemierre syndrome
Let us know how you're doing.