Ed that sucks.
Do you have a pressure test assy for a radiator? It goes in place of the radiator cap and has a hand pump on it with a gauge to check leak down. If you want to borrow one I can help.

If it is a head gasket you could run a compression test and see if you have a cylinder leaking. I have one of those too.

What ever you need it's free and a phone call away.