Bilateral frozen shoulders

Hello

I am a 41yr old white female living in Scotland.  I have had pain in my left arm for 6 months and my right for 4 and have finally seen an ortho specialist who has diagnosed bilateral frozen shoulders and I am awaiting a date to go in for steroid injections into the left shoulder, then the right 4 weeks later.

My question would be why me?  I am not diabetic, I have had no shoulder surgery or injuries to either shoulder.  My past history is of:  ?Spincter of Oddi dysfunction (gallbladder present), Kyphoscoliosis (recently found to have had Scheurmann's Disease), Positive AMA (anti-M2 type) of 1:160 (with normal liver function other than following a SOD attack), Hypothyroidism (stable for 10 years) and Vitamin D deficiency.  Do any of these conditions provide any hint as to why both my shoulders are affected?

Many thanks for your consideration