You could try Instead cups (www.softcup.com - they're available at CVS and I think Walgreens too) if you're desperate.

But really, spotting (or even sex with any light flow) is not a big deal at all. I recently spotted for a month and a half after getting my IUD, and there was sex aplenty with no problem. If you're concerned about a mess, have a box of tissues or baby wipes handy and lay down a towel. But yeah, douching is just bad for you and it wouldn't do anything anyway, since the blood is coming from your uterus, and the douche doesn't - and shouldn't - reach there. :)