Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain Flucillin contains Flucloxacillin while Calvapen is Phenoxymethylpenicillin or Penicillin V and both these are Penicillin group of antibiotics and intake of antibiotics commonly causes side effects as disturbed digestive functions as the antibiotics can kill good bacteria of intestine along with harmful bacteria leading to impairement in the intestinal function.. It is a temporary problem till the antibiotics are being taken.. You can take more or probiotics like Yoghurt in diet as it helps in retaining useful bacteria in intestines.. Take empty stomach Pantoprazole in the morning.. Take Loperamide or Furazolidone to control diarrhea.. Take oral rehydration salts by making solution in water to cover for electrolyte balance.. Tale banana and cereals.. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.