The water will stop intermittently in our bathroom. Oone time in the shower and once in the sink. It comes back after a few seconds. What may cause this?

More details please! Is the rest of the house okay? Are both hot and cold affected? How about the toilet? Does is stop telling for a few seconds? Are you on a well or city water? Anym if you're on city water do you have a pressure reducing valve installed? Let me know. Back to you, Tom