You do not necessarily have a fever
A temp of 99.5 f is normal late in the day. If you reach 100 f or fail to get as low as 98.6 f during a 24 hour period you are considered febrile (having fever), but even then it may not be clinically relevant. The question is why are you on antibiotics and what was the diagnosis? If this is viral you certainly don't need these. Hope you are better soon.