I'm so sorry you're going through this.
Are you planning on finishing out the semester or withdrawing now? If you're not attending school at the time of initiation, you may not be able to be initiated - which would make your decision for you - but you could possibly remain a new member and be initiated in the spring if you return to school by then.
Is there a sister or two, or one of your pledge sisters, that you're particularly close to? Your big, maybe, or your new member educator? Maybe you can talk to them and go through your concerns?
Hope everything works out and that you recover from your medical problems.