
I would phone my vet and ask for advice over the phone. Sometimes pressing an icecube against the nail will help. There are styptic pencils you can buy specially for this; or alum crystals or potassium permangenate are both good, but that doesn't really help now!
:)
Edit: Or is it Permangenate of Potash? Or are they the same thing? Is there a chemist in the house?
:)