I have been told my bathroom shower grout is leaking causing the ceiling below to be discolored. They have told me I have to replace all the tile. They said it doesn't work to just recaulk-is this true. I need advice ASAP

First! Who told you? A plumber after testing to see or a neighbor off the top of his head? Something doesn't sound right to me.
They said it doesn't work to just recaulk-is this true. Replacing all the tile for a grout leak sounds like overkill to me. Are you sure it isn't a faulty seal on the drain? Has it been tested for a bad drain?
Where are you getting your advice from? Let me know, Tom