I have a spasm in the webbing of my left hand between the thumb and index finger. sometimes my thumb/index/middle finger will twitch. what could it be?

Nerve pressure: Could be pressure on the nerves in the hand, or muscle spasms due to use or overuse. Try ice, massage. Try to determine what actions trigger it.

The most common: ...cause of symptoms like these is irritation of a nerve leading to the hand. This can be anything from carpal tunnel syndrome & median nerve irritation to a herniated disk in the neck. There are some neurologic disorders that could cause these symptoms. Anyway, if it persists, gets worse or new symptoms occur, you need to see a doctor. Dr. Anne.