My 2.5 year old son have grommets in both ears. he currently have a bit of a cold, and there is fluid draining from his ears. should i be worried?

Not particularly: During a cold the Eustachian tubes are often swollen/non-functioning. The grommets allow the natural middle ear mucus to vent/drain out the canal (instead of the Eustachian tubes), removing the chance for it to feed germs/support an infection. If the drainage has pus in it the grommets allow any infection to be treated with ear drops.