brake question/problem. i have a noise. help please

my 00 GT is now making a squishy-creaky kind of sound when i mash the brake pedal ( stopped and moving ). sort of fluidy sounding. brake fluid is full and car still seems to stop fine. seemed to start kind of all of a sudden. it sounds like its coming from around the brake pedal itself but im not totally sure i done a visual inspection under the dash. everything looked like its suppose to but then again, not really sure what im looking for


any help will be greatly appreciated

thanks

cant really get a vid for you.

there is a rubber accordion boot under the dash and it sounds ( but it may not be ) like the noise is coming from there


note- didnt make the noise when i drove it this morning