Knock sensor? Spun bearings? Confusion.

Im having a loud knock in my engine. I have attempted a valve adj. At one time and quieted my tick, about two weeks after the adj. My tick came back and became louder and louder. I noticed while exiting the highway while slowing down I no longer had a tick it became a knock. My neighbor suggested it was a lower engine issue, I agreed thinking spun bearings, now Im not so sure, my oil light comes on at lower rpms and goes out at around 2000rpm any suggestions could be helpful.