tired 3 year olds?

Jake had a tummy bug last week and we had a pretty big weekend, but Jake is unusually tired this week - as in, falls asleep at 6:30pm (prior to this he wouldn't go to sleep til 8-9) and he wakes around 8. Was initially thinking he might be low in iron so bought him some stuff for that today, but just wondering if it could be a growth spurt? Mum of course, when i mentioned he was so sleepy, freaked out a little, but I would rather rule out other stuff before I haul him in for blood tests - particualry as it seems to be a recent thing, rather than ongoing.

he told me he had a sore tummy - skulled a glasss of milk, threw it up and then had two days of daycare with a "sore tummy". i put that in speech marks because Jake tends to lie - not on purpose, just if you say "do you have a sore head?" he will always answer "yes, i need some ice cream to make it better" - so I am a wee bit suspicious of any ailments he claims to have. he was definitely sick last week though.