OMG, Soccer! Your story is almost identical to my daughter's! When she was 14 she went for a rebound in basketball, got tripped, hit her head against the floor and then a fellow player fell on top of her head, giving her another impact. Then, three weeks later, a classmate was retrieving his full backpack from on top of the lockers and accidentally hit her in the head.

I'm going to cut and paste from another entry what helped her, but I first must reiterate what others have told you above, and that is to avoid all contact sports until at least all of your symptoms have cleared up. As a mom, I knew how devastating this can be, as I saw what my daughter went through, but it's crucial to your recovery. Your brain is now sensitized and even a small impact that would have been benign before your injury can set you back.

That being said, find some extracurricular activity other than sport into which you can channel your energies. For her it was chorus. Yeah, it's not cool like sports, and that was a big adjustment for her, but she has developed a true passion for it and has amassed a great group of friends.

Anyway, this is what helped her:

(1) EFFEXOR -- Technically an antidepressant, but in small doses helps to re-establish nerve pathways in the brain (She first used Elavil, but Effexor has fewer side effects); (2) ACUPUNCTURE; (3) OSTEOPATHY; and (4) HOMEOPATHY.
She didn't do all of these concurrently; for example, when #2 didn't seem to help any more she moved on to a practitioner who combined #'s 3 and 4.

I hope this helps. Best of luck to you and keep us posted.