Eric (and Ken) hope you feel better soon. I haven’t referenced the Egoscue book yet but have heard good things about it.
I have no experience with inversion tables, but thought a foam roller might be of help with your issue and it’s invaluable for overall flexibility and preventing injuries. I’m referring to the large black ones, stiffest available, 36 in. Long x 6 in. diameter, $19 on Amazon. Lots of youtube videos to show you how to use it.
Why? Sometimes numbness and pain can result from a nerve that’s being pinched due to overly tight muscles, sometimes because the muscles are pulling on your pelvis and/or lower back. Given that your numbness is in your toes, tight glutes, hamstrings (and even calves) can do that. I had a pain in my shin and foot that I’ve all but eliminated by rolling and stretching glutes and hamstrings before exercise and in the AM. And bonus, you feel great afterwards. Also very effective on the upper back to base of neck and front of the upper leg.