Bath tube plumbing is making vibrating sound then...

Question

The bath tube has a facet / handle shower unit mounted together. One must sit in the tub and take the hand held unit to shower. The problem is that a week ago the water would shut off soon after coming on. I would switch the water to run from the facet then back to the hand held shower unit. It seem to work. Two days ago it shut off completely. Today I turned on the water and it began to flow at low volume rate. When I increased the volume it began making a vibrating sound and the water stopped flowing. I removed the shower unit thinking that there was air in the line causing the impass. It did not work. I have turned on all of the up-stairs facets at the same time thinking that if there was air in the line it would pass. All other facets operated properly but the bathroom tub facet.