I think that your first priority is to get well. Take whatever time you need and get the appropriate medical attention. My best wishes are with you and I hope you will fully recover as quickly as is reasonably possible.
SUNY Buffalo is very good. It sounds like you are doing very well there, or at least were doing very well until you got sick. With a 3.92 over five semesters, your high school grades do not matter anymore. You have shown that you can do very well at a very good university.
I do not see any point in retaking the SAT. The SAT is intended to help access the readiness of high school students to do well in university. You have already shown that you can do well in university.
You need to make sure that your current university understands that you are still undertaking medical care, and will not be ready to continue your education for a while. Then when you are ready, you need talk to your current university about restarting. Then you will need to get a new student visa but I do not expect any problem there assuming that you can afford your education.
I agree with other comments that transferring to a different university to complete your bachelor’s degree does not make much sense. You are already enrolled at a very good university.
I would say re-enroll at UB. When you get your bachelor’s degree, if you want to apply for a master’s degree or for any other graduate program, then with a 3.92 GPA from a very good university plus good business experience you would be quite competitive at any university. However, it sounds like your company is doing very well and you might want to focus there rather than study towards any graduate degree.