I've had fun with the new can (my 1st) a YHM Phanton 223/556 on my 14.5 but the one thing that bothers me is the gas blow back in my face. I was shooting a match weekend before last (my first with the can) where on one run we had to go prone for some longrange shots & the gas was going under my glasses & causing my eyes to water really messing up my shooting.
Is there somthing I can do to avoid this, play with my gas system, use different power, etc?

Anyone else have this problem, is it common?

It's a common problem. I use a PRI Gasbuster charging handle and it works pretty well.
Link

Or modify your current charging handle or your forward assist .
a link to what I was talking about mod ch
and gas vent FA
and here is a low pro adj gasblock pri

Hmmm I currently use a amdi Raptor charging handle that I really like, was not wanting to get rid of it but gas in the face sucks.

Or get an adjustable gas block and fix several problems at once. No gas blow back, cleaner bolt and upper, even less recoil for faster follow-up shots.

Yep a adjustable gas block seems like what I need just need to find one that will fit under my slim 13.5 GPI rail that I can get to & adjust.

So which adjustable gas block do I want, it will be under my rail so it needs to be small?

This is the easy sure fix.

Go with either the Syrac Ord. or SLR block. They are both really lo profile plus they lock into position so you don't have to worry about it moving.