just throwing something out for the future...I had a bad mite problem with a bearded dragon a few yrs ago, and my mom is a hairdresser, so I used "Tea Tree" natural peppermint shampoo to soak my dragon in the bath tub....it made the mites very irritated and caused them to fall off and drown.
dont know if it would work with ticks, but its all natural and ticks and mites are in the same family, so theoretically it would be worth a shot.