Strange Feeling at Crusing Altitude

I was on a flight from PDX to Long Beach, CA and at moment the plane leveled out at our crusing altitude my husband and I got a very light headed almost dizzy feeling with a feeling of pressure. I fly often and I have never experienced anything like it before. Can anyone explain what might have happened

I’ve had dizzy feelings before but that’s when I was in a Cessna 150. To me it sounds like something to do with the cabin pressure.