2000 Pontiac Firebird Oil Pressure Problem

Hi all. I own a 2000 Trans Am. I just changed the oil a couple of weeks ago, using synthetic oil, as I have always done in the past. Now the oil pressure gauge keeps going up and down at odd intervals. I don't want to ruin the engine but this is my primary source of transportation. I'm hoping it is just the gauge that needs to be replaced. Any thoughts? Thanks!