Why does my brake pedal go all the way to the floor when pushed on?

I have a 2001 Toyota Camry. I recently had to have a new brake booster installed about 4 weeks ago. Car was driving with no issues and then a few days ago out of no where when I was coming up to a red light I stepped on the brake to slow down. The brake pedal went all the way to the floor. I had to keep pumping the brake pedal to try and slow it down. The car slowed down however it did not come to a complete stop. I had to use my Emergency Brake to completely stop. I nursed the car back home (issues continued all the way) and I have not driven it since. I checked all areas where brake fluid could possibly be leaking from and have found no leaks. I have also continued to check the main brake fluid resevoir and the level of fluid has not dropped at all. I am trying to find out what is most likely the issue and/or if the recent brake booster repair could have anything to do with the current problem