High crankcase pressure caused oil leak?

I got a couple very brief low oil pressure alarms and finally was able to read it the third time before disappearing. I checked the oil pressure switch it looked fine. I checked the oil level it was very low. I looked underneath and it looked like it was leaking from the upper oil pan. I removed the oil fill cap again while the truck was running, and the fill cap had excessive pressure. My year model has a sealed CCV box with no serviceable filter. I wanted to check for a clogged PCV valve but don’t know where it is.