ensuite problem

[monkoss]

I' m in my home 4 years, a newly built house. My ensuite is very small and lately i notice that when i run my taps in the sink the water in the shower plug hole starts to gurgle and run, the same when i flush the toilet!!1! how can this be , it def didn't happen before?? I've put some Mr Muscle down the shower plughole in case it was a blockage or something but it seems to make no difference? Any suggestions appreciated.