Some time ago a friend had me cat sit her darling while she was away on a business trip. Also during this time, her home was having workmen in and out constantly (don't remember now if it was rewiring or redoing the kitchen...). Her poor darling was very stressed and started chewing the fur off her tail in a ring pattern. Eventually things got back to rights when the workmen left and my friend was home for her baby. But she blamed me for not looking after the cat well enough so that it got stressed (didn't do wonders for our friendship) ...

Per her vet, it is better to handle this stress related chewing as early as possible.

Good luck.