I may be making this up but I would imagine that the sensory nerves again are sending mixed up messages to the brain and then a mixed up message is being sent to the motor neurons so they stimulate the muscles to do the wrong thing and you lose your feet for a while - also the numbness in the feet mean you are not as aware of your surroundings so you may not lift your feet as much as you need to to clear the ground so you end up stumbling.
i have the exact same problem with stumbling and not being able to sense where my feet are at times.
Anyway this is only my theory someone in the know may come along and correct me-it is a long time since I studied this at Uni and my brain fog is quite bad at the moment.-I am having Lidocaine Infusions to help me with pain and this has worn off - I am waiting on another treatment next week so it will be sleepless nights and lots of pain and brain fog until then boohoo!