I don't know.

[Frisk E. Coyote]

I say... yes. Sometimes its best just to quit and start again, but this time you'll know what mistakes not to make. It would be so much better than holding on to something you have already given up on internally. This way you can focus on the two subjects you're doing great at. You might as well try and excel at them instead of keep poking around with the one you've lost all hope in.

You've gone quite far, most probably spending the majority of your life going to school to get an education. You're nearly at the end of it, all you need is just one more push and its a whole new level for you. If not... you can always try again. Work hard, play hard, rest hard. Laziness is in everyone, even if they don't know it. You just need... uh... interest, as hard as it sounds. I myself HATE Maths, therefore I have no interest in the subject, and I'm doing mediocre at best. You just have to find a way that'll make the subject appeal to you, like secretly doing it for the pretty classmate/teacher!