Long shot, ............but the spring in the oil pressure relief valve may have broken allowing the oil to flow freely back to the oil pan from the filter canister. Or the valve plunger could be stuck open allowing same. Unusual, when the stick, it is closed, and is more likely to result in high pressure readings.
A quick check would be to stop the engine. Remove the top to the oil filter canister. Observe if the oil drains back into the pan, or stays in the canister. If the spring is good, I believe it should push the plunger out to where the oil can not flow rapidly back into the pan.
You can also pull the square headed nut that is in the block just below the canister drain line to access the plunger, and spring to check it.