How to Repair Stains and Cracks From Bathroom Leakage Information, help and advice on many architecture, self build and design problems and issues

[vladyana]

Hello! Not sure where to post it but need help desperately. Our son turned on hot water in bathroom and water went all the way downstairs to the hall, now we have these ugly yellow spots and cracks. I don’t even know what to begin with and how to repair it, please help.