What Causes Stomach Upset And Diarrhoea While On Zofix?

I had taken Zofix 200mg and Calpol due to fever (my doctor had precribed). After taking two doses of each my stomack got severely upset and loose motion started. Now I have stopped Zofix. I started taking Ridol to stop Loose motion. Please advise what to do now as I am very weak although loose motion has reduced (not stopped totally. Please advise.