Can foot numbness come from change in level of physical activity?

Yes. There are a number of factors that would influence foot numbness and activity level including pathomechanics, impingement syndrome, peripheral edema, shoe stability/fit/type, metabolic syndrome, repetitive injury, incomplete rest from previous injury. An examination is indicated.
Yes it can. You could be using muscles that are swelling and pinching on some nerve.See if it gets better with rest.

Related Questions

Can foot numbness be caused by a change in physical activity?

Yes. Tarsal tunnel syndrome may be worsened by marathon running or vigourous jumping. Involves entrapment of posterior tibial nerve at medial ankle. Getting off feet may help. A good podiatrist can benefit all of this. Read more...