Legal Question in Landlord & Tenant Law in Georgia

If the lease says you can (or you follow an early termination provision). That would be unusual since landlords don't generally undertake responsibility (i.e., the expenses of lost rent) for their tenants' medical issues.

No. A lease is a contract and is binding on both parties. A note from the doctor won't cut it. The only way out is if the lease has some sort of early termination clause, which I doubt. The only thing you can do is bite the bullet and negotiate with the landlord.