Yeah, the tight hams are related to the back pain, but it's probably the other way around: your back is most likely the cause of the uncomfortable ham tightness.
Short hams are not pathological in and of themselves. Lots of athletes have "tight" hams, that's a source of their quickness and strength.
Uncomfortably tight hams come from somewhere, they don't just spontaneously get too tight for function. In women, particularly, the hams will step in to try to stabilize something goofy at the pelvis/lowback/hip. Since you are reporting back pain, I'd guess that whatever is causing your back pain is also triggering your ham muscles to jump in to help.
Do you do the cobra in your yoga practice? Next time your back hurts, drop and do 10 cobras (hold 'em for a second or two) in a row. Does your back pain change as a result?
Do you have a PT?
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson