Low Oil Pressure Guage & oil in engine but not in filter?

Driving home after a 180 mile trip and Oil was done 8 days prior with new filter & lube I get a "low Oil pressure reading" Light comes on & buzzer I am like ????? I pull right off the road & check the Oil is fine clean & golden color then recall 3 years prior had almost same issue with sending unit/ pressure sensor I should say I replaced it and all was fine so just to be safe called my mechanic & he says same it's sensor no bangin/ no noise engine ride's smooth drive home will take care of/ so I drive addt'l 40 miles home / my guy gets jeep checks sensor just to be safe changes it not issue? does pressure check as well,tryed to back pressure to see if blockage & nothing ? @ this point he has engine filter off no oil coming out & engine running purring like kitten for a min or so & no oil commin out????? {{{{{{{could it be the oil pump}}}}}}}? Guage move to center then back down to zip a couple times then hardly moved at all >This is while driving !
2003 jeep wrangler 114.000 miles /// just did timing chain & water pump on it 4 months ago as hit 100,000/ just to be on safe side