4year old has very swollen tonsils should i be worried. he suffers from tonsillitis ?

Hard to say: Most 4 yo will have rather large tonsils compared to teens or adults.Tonsils grow faster than the kid until about 8, when they slow & stop.By their teens they seem smaller unless infected frequently.If the kid snores a lot & stops breathing for >10-15 sec while sleeping, he should be evaluated for sleep apnea & see an ENT.