As Theta said, it is unfortunate that your are going through this.

I suggest that you get armed with some understanding of concussion and approach your host family for support. With proper understanding, they can be more of a help for you. There is a saying, it is better to be close to an enemy you know than an enemy you don't. It will be safer for you to discuss your condition with your hosts so they will not over-react to any time of severe symptoms. If they have your condition sprung on them, they will be at a big disadvantage and may over-react.

It will help if they understand that you are taking steps to help with your recovery. Continuing to put your brain at risk by playing basketball will not be in your favor.

If you can get a copy of Dr Robert Cantu's new book "Concussions and Our Kids" they can get a good understanding of the risks of you continuing your stay in the US. The risks are low if you moderate your daily activities. You will not get any better care in Germany so going home will not change anything.

In fact, the book may be the way to introduce them to the facts and such about concussions.

My best to you.