Clicking from motor. Getting worse

Hey guys

I have a 2008 wrx with 21xxx miles and a few weeks ago I started hearing a hissing or whistling noise at speed. at first I thought it was wind in my helmet but after a few days it progressed to a clicking seemingly from the left side of the motor that is matched with the rpm. I figure it has something to do with the timing chain tensioner or the timing chain itself smacking against the engine. How do i troubleshoot this? I already took the tensioner out and it seemed to be functioning (but i dont really know, Im not familiar its just that it would not push in freely) anyway i reloaded it and put it back in and nothing changed. Im not sure how to determine if the tensioner is bad or my timing chain is stretched and i need a replacement.

Thanks in advance for any advice you can provide

-Colt