The hot water in the kitchen has low water pressure; but the cold works great. When I take a shower I try to use just a little bit of hot water. When I do the pipes start rattling really loud behind the wall of the shower. It's like they are going to shake through the wall. It scares my youngin's to death. Thanks for any help with this issue.

Hi Tracy and welcome to The Plumbing Page at ANHD.com.Sounds like you have several issues here.
In your kitchen try this. Shut the water off and pull the cartridge, Check the inlet ports for trash and clean. Now place a pan over the open valve and turn the water back on for a minute to flush out the supply. You should have a strong stream when doing so. Reassemble and test. If that works do it on all affected taps
What type of tap do you have in your shower? One handle or two knobs? Back to you, Tom