Shower is leaking into the bilge

I am a new owner of a 41 pc 1997 When the shower is turned on the flow is almost nil and the water runs into the bilge It must be the line from the shower handle to the shower head has burst during the winter. my question is How do I access it? Iam stumped

Can't help you with access but maybe TAG could give you some pointers. So are you sure you have ONE problem and not two, meaning the light flow coming out is an issue and water in the bilge could be from a sump pump issue, perhaps the shower head needs to be descaled and your sump pump isn't working? Good pressure at other faucets? Or can you hear water spraying around the shower wall, I'd think if a hose were busted you might be able to hear the noise.

Thanks for the tip on TAG the shower head is new the pump is new good pressure at the sink faucet With the head removed water flows but when finger pressure applied it stops and you hear the water running into the bilge. I'm guessing the line is split but I can't confirm what I cant see and trust me its not for lack of looking