Did you stop UT as soon as you got the chillblains? It sounds like your body was experiencing a healing crisis, which is typical when undergoing natural therapies. If you're willing to give it a try, you can continue with UT despite the chillblains and see if they eventually go away.
I used to suffer from migraines. When I started on UT, within half a day I started to experience a migraine that went on for the next three days. But I had read about healing crises, so I persisted with the UT and the migraine stopped.
Google "healing crisis" and you will find many articles that explain the concept.