Is there somthing wrong with my cat?

I woke up this morning to my cat making a sound like gaging...and then I heard it again about a half an hour later but this time it kind of sounded like a dog whining....he hasent dont it since (from what I can tell) but he is breathing kind of hard and his meows are kind of scratchy...He can still purr tho...I would come to pet him and he would pur like nothing is wrong...oh and also when I got out of bed to see what was going on there wasnt a hairball or anything near him...He hasnt made any abnormal sounds since but when he sleeps his breathing is still at an abnormal rate (his stomache goes out and in a lot more than it usually does) is the serious enough to contact a vet??