Do you have a test kit to measure your levels (FC, CC, pH and CYA)? Are you using the method from the "How do I use chlorine in my spa?" sticky thread to chlorinate?
What I would do is raise your FC to shock level using the Chlorine/CYA chart in my signature. Reduce the temperature in the spa to the lowest setting or off. Cover the spa. That alone would get you through 4-5 days imo. You could also put in a 1" tablet floater with 1" trichlor tablets for some insurance. If you do that, only have the vent/opening on the floater open slightly. This may raise your CYA just a bit, of course.