That kind of skin reaction often is due to some hard core drug use, though that is just wild speculation on my part - you see that with Meth or other bad street drugs.
Many black people have bad complexions. When I served in the US Army I saw some of them shaving with a cream and a butter knife, because a razor blade did damage.
If she has wandered from Portland, to Texas, then Lost Wages with her 3 year old, attempting to sleep in he vehicle, her life isn't in the best condition it might be.
But nothing, not drug use, not poverty, not homelessness comes remotely close to providing a motive for mass murder.
Most of these incidents are young people, and I believe they have distorted concepts about life. They hold unrealistic expectations, about what they are "entitled" to expect-and to receive.
To hear them talk psychobabble learned in school, they made "bad decisions" and they used "inappropriate response control."