How often should he poo?

my LO is 15 months & is still a poo machine. one day this week he poo'd 8 times in 24 hours. not diarhoea, but just normal poo (reasonably loose). he has also had really bad nappy rash this week & has had a couple of bad tummy aches recently (after being looked after by his nana). He is teething at the moment, he's go back teeth coming top & bottom. Is this amount of poo normal? he's always been a big pooer even when he was new born. generally he poos after each meal & not normally at night, but this week he even poo'd during the night!