Why is my sourdough starter so active in less than 24 hours and why does it smell weird?

See Debra Wink's microbiologist's view of the birth of a starter on these forums. 

Short version, what you have there is not unusual but it is not yet a starter, you have to carry on watching and feeding.

Yeah the Debra Wink posts are really good on this. Basically you're gonna have a bunch of stink and activity for a couple days while you wait for the pH to drop. Then it will become more liquid and quiet. Then you'll start to get toward a real starter. If it's too liquid after that point you can lower the hydration a tad.

You can speed up the process by lowering the pH a bit, e.g. pineapple juice. Though you don't want to lower it tooooo much, e.g. vinegar. And at this point that activity is lowering the pH, so you're already on your way anyway.

Further good news: you'll never need to buy yeast again.