Hi and welcome to the forum! I am glad that I can help you.
You want to know the cause of the symptoms that you experience.
Increased body temperature, sore throat, enlarged tonsils, nasal discharge and congestion may indicate viral or bacterial tonsilopharyngitis (inflammation of the tonsils and pharynx). In cases of viral infection individuals experience fatigue, muscle pain, fever, red throat and tonsils, but no pain when swallowing. In cases of bacterial infection people experience enlarged tonsils with or without pus on them, increased body temperature and pain when swallowing.
Given the data that you described, you may be experiencing a bacterial infection. You may consider stopping the antibiotic treatment for a couple of days to have a bacterial culture with an antibiogram from a swab sample from your throat to exclude possible bacterial infection. You may consider taking antibiotics according to the antibiogram results.
Please keep in mind that I provide medical information only. I am not able to diagnose medical conditions online. Please contact your doctor for further advice and information about diagnosis and treatment options.