Im sorry to hear about your girl. Id say the flush was a good Idea, It is normal to have leaves around the bottom of the plant go yellow, Im always pulling them off as she goes, doesnt seem to be a big problem for me at least. Being outside could mean a bug issue, Ive herd some gnats have larva that eat at the roots? Check to see if you roots really close to the surface, maybe add some dirt on top, I actually found a lot of roots closer to the surface to I added an inch or two. I dont have any experience with nute lock tho, hope thats not the issue.