I'm sorry to hear your Doxie is having a vomiting problem. It could be something simple to something very serious. I would go with the withholding food for 24 hours. Possibly it's something he ate and will clear up on it's own. Here is a link that will give you lots of suggestions as to what can cause vomiting with bood. I hope it helps.

http://www.2ndchance.info/vomiting.htm

Sending positive thoughts he will be okay by tomorrow. If not don't hesitate to get him to your vets right away.