I wore heels for 3 hrs being on my feet. the next day my big toe hurt badly. i don't usually wear heels. what could be wrong and should i stop yoga?

No, you should stop: wearing high heels! Three hours is a long time to wear uncomfortable shoes that throw your posture off and puts excessive pressure on your balls of your feet & UR toes! U could have strained UR big toe. If it's swollen and inflamed, U can use cool compresses and elevate it, and see if that helps. If not, see your doctor!U can always do yoga from a chair/seated position if standing is hard to do.

Heels are normally: very hard on all parts of the body from the toes up to the hips. Limit exposure to wearing heels unless there is a compelling reason not to. I'm surprised only your big toe is aching. Heels put pressure on muscles in ways not designed, and mess with blood circulation to boot. BTW, what does this have to do with yoga? Continue with that...