Yes, that could be what it is. After the downstairs toilet is flushed it might be quiet for a few seconds and then I sometimes hear 50 kind of squeeks. Also get banging when my new washing machine squirts over and over to rinse the soap dispenser. Actually, I think that may be what started the problem, after a while, with the jerking of water on and off. It seems to be cold water only. I just hope I don't need walls torn up to secure pipes. I hope the plumber knows exactly what the cause is, when he hears it.
I looked up water hammering a couple weeks ago and tried letting air out of the pipes by the water regulator. I thought it fixed it but no such luck. I thought it might have something to do with the water softener and scale but I'm ready for an expert.