Kynan had about 3.5 weeks of diarrhoea when his 2nd tooth came through (up to 4-5 dirty nappies a day!!). It's the only time he's ever had nappy rash. I found using chamomile tea wipes helped as well as slathering him in Botty Butter (Beauty & the Bees). In the end though the rash only completely went away when the diarrhoea stopped.