Frequent Vomiting, becoming more often - Please help!

Hello all,

My cat Myrrh (indoor, neutered 4 year old, long-ish hair domestic) has always been a bit of a puker (2-3x a week) and when I took him to the vet a couple years ago, they weren't concerned. As I am the one who cleans it up and never saw anything suspicious or worrying, I didn't worry if they didn't.

However, the last two months he has been vomiting nearly everyday, once a day. Again, I clean it up and never see blood or anything. He hasn't lost any weight and acts perfectly normal. Once every other week or so there is a small hairball, but other than that it is just food freshly eaten or mostly digested with no pattern to go by. 

He goes to the vet on Friday because I know this can't be good for him and I can't imagine throwing up this often now to be "okay." His other 3 friends are just fine. There has been no change in the household or other stress that I can think of. His food has been the same for 2+ years. He is inside 100% of the time and has acted normal besides the frequency of the vomiting. Has anyone else run into this problem before? 

Thanks for all insight!

This is actually a fairly common issue but has different causes.  The cause can be difficult to figure out.  What food is he eating?  Kitties can develop an issue with a food that they have been eating with no issues.

He's been eating the PurinaOne Urinary Health formula. Not the best, I know. My other male cat has a history of urinary issues and this just worked for him. He has been on several foods, but he has been fed this one for two years. I suppose it is worth a shot to switch it up.

Is it dry or canned?  Many times kitties are allergic to ingredients, mostly grain in the dry food.