Here's what you do (coming from someone who can't afford dental care and has a few very bad teeth right now)...
1. Garlic clove - bite down on it over the offending tooth, the garlic has anti-fungal and anti-bacterial properties (like antibiotics) that will kill infections. It's infections that cause the pain of a tooth ache.
2. Onion - same as garlic
3. Peroxide - stings for a second but instant relief. Take a q-tip and dip it in peroxide then put it over the offending tooth and bite down. You'll feel a bit of a sting, bubbling and then relief.
4. If it's a cavity, tooth gum (any pharmacy should have it) with a bit of clove oil. A few drops of clove oil in the cavity then pack it with the tooth gum. It's a temp fix before seeing a dentist.
last one WILL destroy the tooth more but oh so nice for relief and instant relief:
If you have Advil in liquid capsule form, break open a capsule and squeeze a few drops on your finger, swipe this across the tooth - total instant relief!!! For hours!!!
WARNING : tastes like the worse thing you can imagine, do not rinse tooth but you can drink and eat as normal. It will make you gag the first few times but you get used to it. Any liquid capsule form of Advil works (regular, migraine, ect)