Lui,

It is sad to hear that you are still suffering so. You have had some unfortunate experiences indeed in your brief time here in the US.
I wish that were not so for you.

The ear ringing is the tinnitus.
As Mark indicated, it is very common with pcs. Are you listening to iPod or mp3 player? Loud music of any kind? Perhaps soft, low-volume, easy-listening music on your iPod or mp3 would help to avert your attention.
Perhaps a low-level of music/radio at night to go to sleep? Just a suggestion.

You asked: "So, is it even possible to get pcs which is lasting so long from heading a soccer ball, I mean come on! "
In short, yes, it is possible, as many persons on here have experienced.

What has been your self-care since the heading a ball injury?
Are you continuing basketball? What are your other activities and your schedule? Are you making time daily for the prescribed quiet rest?
Are you taking it easy or are you playing basketball?

However my attention is drawn to the entire gestalt of your unfortunate circumstances since being in the US.
The stress of your former living conditions and uncaring attitudes of your former host family, Ach. Das ist aber schade.
It is good that you chose to change host family.
I hope that you may be made more welcomed and feel cared for now.
However no one can help you unless you ask.

You do need to talk with someone there, Lui. If not your hosts, perhaps a counselor or a teacher at the school with whom you feel comfortable.

You must not persist with this feeling of "i can't talk with anybody about it because they would send me home."

Die am besten zu Ihnen,
Theta