@anne4u, pain, stress and medications cause a loss of magnesium possibly creating a deficiency. This impacts thiamine and vitamin D as both require magnesium to become bioactive. Vitamin B2 along with activated thiamine are needed to activate vitamin B6. The B vitamins work better together. The first two links offer the effects of B vitamins on conditions similar to some you have mentioned. The ncbi link reviews the fifth element...boron, which often goes unnoticed, yet brings an enormous number of benefits to the table. A Youtube video by Dr. Jorge Flechas MD on boron is riveting. The krispin link is offers additional magnesium information. Always consult your health care professional before using any supplement.
https://www.dsm.com/pharma/en/news/dsm-pharma-blog/back-to-basics-the-impact-of-b-vitamins-on-low-back-pain.html
https://www.healthrising.org/blog/2013/07/19/the-high-dose-b-1-thiamine-supplementation-survey-fibromyalgia-chronic-fatigue-syndrome/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4712861/
https://www.krispin.com/magnes.html