Water pressure not sustaining on city water

[Roodman]

Hey all- I've got a 1994 classic. Been in the same location for a year so I don't move it often. I'm at a campground. Water pressure has always been good. Had a big freeze and hose froze. Since then my water pressure is not good. When I turn on sink I have good pressure for about 15 seconds then it goes down to a trickle. I unhooked hose and the stream is still on the city side. Took off pressure valve and that didn't help. Anything else I can/should check? I don't see any leaking underneath. If I shut off sink and wait 30 seconds I have a strong flow but again only for 15 seconds