Urgent help: sinks to bottom, can't balance...

http://www3.telus.net/henryho/fish/001.jpg
http://www3.telus.net/henryho/fish/002.jpg

This is a little gold fish keeps on the bottom, like sleeping.. but can't
keep its balance... I wonder if I fed him too much as his belly seems to
have a little black. I think the poo-poo is stuck inside?

I've read that feeding peas might help... should I do it? What about the
epsom salt that many sites talk about, would it help? where should I get
them in Vancouver, Canada?

Thanks in advance~