I'd say, do it.
I started running in January 09, for the reasons you mentioned. First, on the treadmill, then outside. I really liked it, even though I am slow, slow, slow. But, when I got up to 4-5 miles, my right hip/lumbar region started acting up. I would stop running for awhile, start again, and same thing. Finally, after many stops and starts, foam roller, stretching, I stopped in June, after running in a 5K race I promised my friend I would do (a charity race for the hospital she works for).
Well, last week, I realized that all of a sudden, my back isn't hurting! I mean, it hurt all of the time. Now, I am torn. I like running in the fall and winter; when I run and ride at the same time, at age 56 (almost 57), it seems to affect my cycling a lot. My legs are really heavy/sore. I do ride through early December, but by the end of october, it's less and less.
Yesterday, I did a 30 minute interval walk on the treadmill. I did lots of hill intervals at a 5% grade while walking, and i also snuck in 3 one minute running intervals at a very slow pace (5.6 mph). My back feels fine. But, I am still very uncertain if I should start up again. The fact that you can just go out the door and run, really appeals to me and it keeps the weight down, too.
2015 Trek Silque SSL
Specialized Oura
2011 Guru Praemio
Specialized Oura
2017 Specialized Ariel Sport