You have infection to tonsils, initially it could be of viral etiology and a bacterial culture may be negative as there is no bacterial infection.
You can do hot saline gargles and /or antiseptic gargles like hexidine 2 to 3 times a day.
You may require certain drugs known as decongestant and analgesic
and anti inflammatory drugs along with proper anti microbial drugs.
Please consult a ENT Surgeon as soon as possible.
You will improve in few days do not worry.
Best of luck.