It was caused by stress.
Stress apparently causes some hip flexor or whatever to shorten. At its worst, my right foot at rest is about 80 degrees off of parallel from my left foot (or my pelvis, for that matter). It always has been; the school nurses always tried to get my parents to treat my scoliosis and shit until they eventually gave up and figured out they didn't give a fuck (see also: teeth). Giving it a good crack will reduce that angle by 30 or 40 degrees, and then the next time you might get another 15 or 20.
The pathway to chiropractic on that one was archetypal of the bullshit.
I went to see a doctor because I had plantar fasciitis and general pain while running. The doctor took one look at my chart and said "yeah, your feet would hurt a lot less if you weren't obese, lose some weight" and walked out. Then their assistant decided that maybe acupuncture would help with stress or something, and, since it was covered by my insurance, why the fuck not. The acupuncturist took one look at me and said "fuckin' A, dude, you need to see a chiropractor about that leg, also a podiatrist, here let me throw some needles in your temples 'cuz that's my jam" (except he was Chinese and his english was a lot more formal than that) and then the chiropractor fixed my leg but decided I needed to keep coming in once a week forever because that's their jam and the podiatrist, meanwhile, wrapped my foot, tried to give me cortisone injections and recommended that we sever a couple tendons to my toe because fuck you, that's why. After some cajoling he relented and prescribed me some righteous carbon fiber orthotics which were great and then I lost that job and lost that insurance and those poor orthotics had to last me another eight years. Meanwhile the running store in Los Angeles said "hey, you're running wrong, try out these weird ass shoes and also stop running like that" and then I broke a metatarsal.
Two weeks after the doctor called me fat? I broke a pedal off the exercise bike at the gym. Second in three months. I debated sending it to her and asking for her advice on how, exactly, I lose weight considering I was literally breaking exercise equipment, but never actually did.
It's one of my major life regrets.