Burning oil

[S.rucker]

I have a 98' Lexus Gs 300 & for the past month I have noticed that it's using alot of gas & burning alot of oil.  I placed a white sheet in my garage where I park the car to see if there was a leak & on the sheet the next day were quarter size spots.  I didn't think that was so alarming, but when I looked at the oil stick, barely any oil was on it. So I put 2 quarts of oil in & checked the stick again & it was good. Two weeks later  I checked the oil stick again & the same thing, it barely registered on the stick.  There is no smoke coming from my exhaust & no oil light has ever come on to say the oil was low. The spots on the sheet are still very small, so where is the oil going & why is it burning so much gas?