Well, first of all, not to discourage you, but SRV, Clapton, Hendrix, and the like all had extremely good ears. Second of all, experience.
Now, a good ear is something that can be trained. You train it every time you play, or try to identify something in the music you hear. A better way would be to get a teacher to show you the beginning steps of theory. If you're still in high school, take a music course. You have nothing to lose.
I may get flamed for this, and maybe even hypocritical since I teach theory, but theory is not essential to your playing. Does it help? Of course. You'll be able to recognize what you're playing and hearing in a whole new way. You'll be able to group your ideas more clearly and be able to come up with stuff that doesn't come easily without theory.
Just keep in mind that theory is in no way a set of rules, it's just a way to communicate your musical ideas.
