On the petitions for revocation of probation that I've seen, health reasons, aren't normally defenses to violation of probation. The reason this is so is because if you had to leave the State, you could have had your probation transferred out of state. Furthermore, you are not permitted to change your place of abode without permission of the probation office.
All this being said, I would be very worried that a probation warrant is already outstanding. You need to at least touch base with a GA attorney before you turn yourself in. This will make bringing you to court easier.
I am sorry your health prevented you from returning. However, most judges will consider all the circumstances regarding your failure to report. The longer you go without reporting could make the situation even worse for you. I also recommend you speak to a Criminal Defense lawyer here in Marietta to help with the situation.
A local attorney can help you with your options.