SERIOUS corn snake feeding problems, help please!?

I've had my adult corn snake for a little over a year now, he's probably about 4 or 5 years old, and he used to feed just fine, always two adult mice, frozen thawed, once a month. Last two feeds he regurgitated, the one before he didn't, but the one before that he did. He's looking a little on the skinny side, and a few weeks ago when I was cleaning up his feces, I noticed what I'm pretty sure was a little bit of blood. Is this something serious I'm not aware of? Or am I just being paranoid (I know sometimes snakes will inexplicably lose their appetite for a couple of months at a time.) And do you advise not feeding him for a month or two, or continue trying to feed him 'cause he's looking skinny, maybe reduce it to one adult instead of two? Thanks, everyone.