Prices were already headed down in Feb, March and then bottomed out for a few days in April. By the time you get your check, you already have a lag of about one month for oil and two months for gas. So a March check would possibly have Feb oil and Jan gas prices. Look at your check run statement that shows what months were paid on. What you actually received is tied to the contracts that your operator had for your area. https://www.eia.gov. I usually can find Cushing generic oil prices at the eia.gov site. It wasn’t working this morning, but here is another site. Crude Oil Prices: West Texas Intermediate (WTI) - Cushing, Oklahoma (WCOILWTICO) | FRED | St. Louis Fed. If you chose the 1Y option on the graph, you can the general downswing started in January.