Yeah, it's pretty intense, and also very nauseating. I've never had the pain really spread, but then I've never been nailed particularly hard, so I honestly couldn't tell you. Worst I've had is passing a small bladder stone. The pain didn't really spread, but was excruciatingly focused.
Meanwhile, as far as I know, the clit is is a massive bundle of nerves that spread all around your "nether regions", so it would stand to reason the pain would radiate to those areas traveling along the nerves.