Series 5 Apple Watch GPS Issues

I received an Apple Watch series 5 cellular for christmas. The GPS has never been perfect but has been ok. But over the last few weeks the GPS has got extremely worse. I do a lot of running and tracking pace is becoming a nightmare. All my location services are enabled as should be. I have pressed ‘Reset fitness calibration data’ in the Apple Watch app and been out for a run again but this seems to have made it worse. Any ideas?