Noob here, please help

[Heveatsbeans]

I drive a '99 Legacy GT 2.5 and have, over the last week, noticed that I am birning though oil. I've kept a careful eye for leaks and there are none, and have been checking my oil every time I've driven more than a couple miles. I've put three quarts of oil in it since noticing it was nearly empty the first time. Today I replaced the pcv valve after reading that it might be the problem, it was definitely full of junk but I am still losing oil after replacing it. My engine also makes a tap/click when switching gears but only started doing so recently and did not so it for the first 5ish miles after the new pcv. But, alas, i am still burning oil with a noise from my engine. Any ideas? I am totally stumped.