5 month old and diarrhoea!!

My LB is 5 months is now 3 days into having diarrhoea...he's not usually regular maybe once a day if we are lucky which is why I don't know what to do. He's drinking his bottle about 4 or 5oz out of the 6 and still feeds about 5 times a day. He seems okay in himself if a little clingy. The diarrhoea is small and looks mucusy which I know can be caused by dribble, its just the amount he's losing to the amount he's drinking is what worries me...Any Advice??