mystery apple

i bought a couple apples the other day but whatever this one is had the sticker fall off. so i dont know what apple it is. it's like kind of small and red with splotches of yellow. its flesh is kind of hard to chew through and hurts my gums a little :(
and it tastes like a sour banana. like 100%. sour banana. it even smelled like a banana when i was slicing it.