Brief Answer:
Might be due to Penicillin Resistance,viral infection or complication

Detailed Answer:
Hi,thank you for posting your query on health care magic.
I can understand your concern.
You are suffering from on and off fever even after taking 7 days of Antibiotic-Penicillin.The possibility for this situation might be as follows:
1.)Antibiotic Resistance :Many patients do not respond to penicillin treatment .It would be advisable to have a test-throat swab for culture and antibiotic sensitivity-It will guide which might be the causative organisms and to which antibiotic,they are sensitive.
2.)Viral infection-tonsilitis may be caused by viral infection like Ebstein burr virus( causing Infectious Mononucleosis)which does not responds to Antibiotic.You might need to undergo a test called Monospot test to find out whether the cause is Ebstein burr virus.
3.)Complication of Tonsillitis:It is important to rule out complication of tonsilitis like cause such as retropharyngeal abscess ,Peritonsillar Abscess by throat examination with an Otolaryngologist doctor.
Treatment of acute tonsillitis is largely supportive and focuses on maintaining adequate hydration and caloric intake and controlling pain and fever
-Also take Anti-inflammatory and Analgesic like Ibuprofen to reduce the inflammation and pain
Reinforce your immune system with Vitamin C, and drink a lot of clear water to purge the virus / bacteria away.
Hope this answers your question.I would be happy to answer if you have any follow-up questions.Get well soon.

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Brief Answer:
Happy to hear about your health improvement

Detailed Answer:
Hi, XXXXXXX thank you for your reply.
I am glad to know that your symptoms of tonsillitis have resolved and you are feeling better now.
Take care.

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