hi there ,
the symptoms you are describing is most probably a viral fever
.it is unlikely that it is due to augmentin
because it has occurred after stopping the drug.i would advise you to take bed rest
, plenty of fluids and an antipyretic
for the fever.it should subside in a few days. if it persists then show it to a doctor.as far as your competition is concerned, better to take rest till the fever subsides or you wouldn't be able to give 100% to the competition also.get well soon.