Hi
@Trinny 
Welcome To BYC
Do you have any photos or a video?
How often is he sneezing?
Any other symptoms like mucous from the nostrils, facial swelling, watery/bubbly eyes, coughing, wheezing or lethargy?
Watch to see when and how often he is sneezing. Is it when he scratches through bedding or during/after he eats, or is he continually sneezing and having difficulty with other respiratory symptoms.
Sometimes dry dusty bedding/feed, poor ventilation, getting food/dirt in the nostrils or molds can also cause sneezing. Watch to see that he is drinking/eating well, look at his nostrils to make sure they are free of obstruction and evaluate whether it's illness or environment causing sneezing.
You can also try something like VetRx to see if that may give him some relief, if he has not other symptoms.