I'd say go back to your old job, if you're on god terms and they care about you then I'm sure they could be flexible with you on scheduling, in addition to that do the internship at SeaWorld as it doens't demand as much of your time. Once you finish school, then maybe re-asses the situation. But in the end do what's best for your future and the future career that you'd like to have.
And don't burn yourself out trying to do too much, you have to have down time with yourself, friends and family.