 [ Symptoms ] back pain for a month now ct scan shows no stone nothing seems to help [ Disease ] no it is not unusual the effects of the illness will still exist because it takes a while a week or so for the bug to be annihilated by the penicillin and your immune system also penicillin increases your white blood cell count and so your own body is still fighting the bug the medication itself does not fight it your body is still going through the purging process of getting rid of the bug so you will still feel sick and tired for a while taking too much penicillin can cause ill effects as well so try not to do that just let it run it is course