Trey's issue is not only troublesome because he's forming clots and those could be life threatening depending on their location and his anatomy, but also the possibility that he could need to be placed on chronic anticoagulation. You can't have someone playing a violent sport such as football on blood thinners. That's a recipe for potential disaster if he suffers a traumatic injury.
Also, I can't think off the top of my head a surgery to perform to prevent blood clots. People have inferior vena cava filters placed to block embolisms from migrating from the lower body to the heart and lungs. But that's a procedure performed to help after the fact. I'm not sure what could be done to inhibit the production of excessive clotting. And if there is such a procedure, I wouldn't imagine it would be something a 20 year old football player has performed so he can return to the field.