What's wrong with my toe?

Sounds like a stress fracture - a small hairline fracture in the bone. Try immobilizing it by taping it to the toe(s) next to it (use 1st aid tape).

It's most likely just stubbed or strained.

When you're at home, try to rest it as much as possible, preferably with your foot elevated on a cushion. If you feel you need to, put an ice pack on it, whilst you're resting. This can help with pain and help reduce any swelling. Also, if the pain turns into an ache, a warm compress will help with that, as heat is amazing for soothing aches and things.

When you're out walking, or using your foot alot, you could try supporting that toe by applying a small bandage, or using speciallised medical tape to tape the affected toe and the toe next to it together. This immobilizes the toe, giving it extra support. You can buy this tape at any good chemist. And maybe wear an extra sock on that foot, just to take the edge off the pressure you're applying.

When I hurt my toe a few years ago in a sporting accident, I found that putting a foam insole into my shoe really helped ease the pain, as it cushioned the toe, and reduced the amout of pressure I was putting on it.

Also, don't play any kind of sports whilst it's still hurting. The more pressure you put on it, the worse you could make it.

Try these things for 5 to 10 days, and it it still hasn't gone, I really would suggest seeing a doctor, because there might be a more serious problem like a cracked or dislocated bone that needs medical attention.

If you stop putting pressure on your toe with a wild swing with your sledge hammer then you will ind that the pain will go gradually away after a few days, it could take longer if you have had multiple swings at your toe over a long time.