I was driving to work breaks were fine on the way I stopped at a stop light pressed the breaks and the break pedal went to the floor and when I went on up the road my breaks were not working that well had to go all the way to the floor I checked the break fluid it was low when I added more fluid it wen to the max line then the break light went off but the ABS light stayed on as I pressed the breaks while the truck was parked I heard air from rear wheel driver side looks like some fluid leaked out back there also under the hood the break fluid was low again whats wrong is it the hose or the cylinder or master cylinder just look for some friendly advice

 

Probably weak/bad brake lines....these model trucks do that sometimes....