Hello and welcome.
Please let me know since when are you taking antibiotics.Do you have diarrhoea
after completion of course or simultaneously?
Though diarrhoea is considered as side effect of penicillin group of drugs but if it is prolonged than it requires medical atttention.
I would suggest to use ORS
that is oral rehydration solution to prevent loss of water and minerals.If the frequency of passing stool is more, than please do not hesitate to see your doctor.
Hope it helps.