Deciding between Mechanical/Biomedical Engineering or Computer Science.... Hardest Choice of my Life

@thetruthbetold71, have you taken any courses in Mechanical Engineering or CS yet? Taking the courses might give you a better idea of what you like better. You might be able to take courses in both CS and ME regardless of which one you declare as your major, but some schools do restrict access to courses in some majors.

You should ask the school if you can take courses in those departments without being in the major.