So a quick explanation:
I started messing with Wordpress a couple of years ago, having experience with HTML, CSS and some PHP. At that time I was paid a few hundred bucks to whip together a customized site for someone, which I had done by really manipulating (basically redoing everything but the functional side of things and the basics of the layout).
Fast-forward to today and the same guy wants to pay me to rework his old site a bit, however it has some layout issues (the mobile layout has shifted to the left from center etc. things that I believe will be fixed by a theme update or some tweaking on my part). Now today I would never work on anything without creating a child theme, but now I must redeem myself for my noob mistakes.
My question is: what should I know/do before embarking on safety-proofing everything as I migrate the changes to a child theme? I know that once I do this my layout will look wonky until I re-add widgets, menus etc. Is there anything I may not expect?
I have edited so many different PHP files in this theme that I am going to have to run some sort of scan over the directory to look for changes/differences in the new files as not to lose any of my work.
Any advice is appreciated, thank you.