What is causing the tingling sensation in my toes?

It's probably sign of some referred pain from the lumbar spine (usually L-5/S-1 disc or sciatic nerve). I'd start by paying very close attention to maintaining your posture, avoiding prolonged slouching, and you may want to consider picking up Robin McKenzie's "Treat Your Own Back"...hopefully, you'll be able to nip this in the bud before it becomes a problem.

Addendum:...yes, it's possible for your leg to hurt without your back hurting...but in all likelihood, you'd probably be in more pain. If that's the case (your back doesn't hurt and the leg pain is mild)...it could simply be a localized compression...sitting on a chair that's too hard for you or too deep for you. In either case, I'd at least start with focusing on posture...

I'd wager you pinched a nerve. Were the heels above all tight or new. Avoid getting heels which can be too tight. If they weren't too tight however simply new, you will have to attempt to holiday them in previous to dressed in them for an extended interval of time. If you keep off heels for a at the same time, I'd suspect that the tingling sensation will have to depart. If it does not after approximately every week or so, or worsen, pass see a surgeon.