Earlier today, i glanced down at my oil gauge, and it was flatlined on zero!

I pulled off the road, waited three hours for a tow, and when I got to the mechanics', upon starting, it pegged to the top of the gauge! Happily, I drove away, only to notice 15 minutes later that at slow speeds the gauge was again reading at zero, but with acceleration, the pressure would rise to two or three. I drove straight home and parked it, and will have it towed to my regular shop on Monday morning. Question--if it is not the oil pump, but rather the sender (hope, hope!) would it reflect the normal rise and fall of the oil pressure, but just be lower? Or if it was the sender, would it quit altogether?
I need some good news today.

Tom
92 500E
127,000 miles