Since it is only been happening this week, the useful question is what changed. Have you used anything near the enclosure: a mite treatment, a flea product on a pet in the same room, aerosols, a cleaning spray, an air freshener. And check your bedding, because aromatic shavings are a common cause of neurological signs in reptiles and cedar in particular is widely advised against.
Also measure both ends with a probe. Temperatures a long way out in either direction will do this too.