Alright,I was driving yesterday and i was playing around with my steering wheel and pressing the brakes to turn into the mall when all of a sudden my brake pedal got really stiff and it barely brake's now and when i do press the brake it makes a really weird hissing noise. Friend told me it could be the booster ? or i have Air or something in my system ? Help !!!

You have lost your booster... you now know what it was like in the 40s without power brakes. That hissing is the calipers barely rubbing up against the rotors along with the booster making racket. Get it replaced ASAP... or get an anchor.