DO NOT SELL YOUR GUITAR! You already have a foundation in it, why would you get rid of it when you can continue learning that along with the drums? I went through the same phase as you where I kept debating "guitar or drums" (I thought I could only master one over the other). Then it hit me, learn both duhhh. I know what you're going though, you're thinking of abandoning the guitar because you see no progress. Here's the news buddy, the drums ain't any easier and you'll get no where with that attitude man. Don't give up just cause it's hard cause they're all hard lol. Stick with it and you'll be happy.
If you need the money for a new drum set, then play on your bro's kit, if not, save your money and buy a new kit later. Remember, the more instruments you know how to play, the more versatile you'll be. So why not learn both? If you ignore what I am telling you, you will regret it buddy
