Cat with diarrhea

My almost 3 year old cat that is on a only chicken meals because of allergies,has had diarrhea for 6 days(once a day)Eating,drinking as normal,showing no signs of being unwell. What could I give her to rectified this.

Hello - rather than asking 'what can I do to make the diarrhoea go away,' I would tend to ask:  'what is causing the diarrhoea?'  Diarrhoea is a symptom of many different disease processes - some short-lived and self-correcting -but it is never normal.  Even supposing that I could give something to a cat to 'firm them up' (and there are things available to try, dietary modifications being one of them), it is still important to have some idea of what might be causing chronic diarrhoea, because the wet faeces / fluid loss may be only one way in which it is affecting the patient.  Furthermore, if the cause has not been identified, it may be difficult to identify a permanent treatment.  Possibilities may include a host of different parasites (worms, trichomoniasis), dietary indiscretions (eating something else in someone's garden down the road), hyperthyroidism, viral disease, allergy, pancreatitis, liver disease and so on.  Good questions for your vet include, 'at what point is it worth starting investigations to try to pinpoint the cause of diarrhoea?'  'What possible causes are there for my cat at this time?'  'Can anything be done to rule some of these out?'   and 'Would you recommend this at this time?'   Best of luck in agreeing a plan with you vet.