I did not experience any pain from Hashimoto's - low thyroid and an autoimmune condition. LDN is an off label use for my condition. The LDN helped rid me of the antibodies attacking my thyroid - this is a very simplistic explanation.
Google LDN and you will find a lot of information about its uses. Inflammation is a major, major cause of many symptoms. It's important to get to the causes of those symptoms and treat the cause not just the symptom. Treating the symptoms gives you relief but once off the meds treating symptoms, symptoms invariably return. I went through that with my digestive issues before changing doctors multiple times and finally being tested for the causes - SIBO, parasites, fungal infection - and treating me based on these causes.