OK - well the picture isn't great but at a guess I think it was a
bed bug. You will find a picture at
http://www.cals.ncsu.edu:8050/course/ent425/text19/bedbug.jpg
but it is very difficult to tell.
Bed bugs do become engorged with blood and then when squashed like
yours is go small again.
I hope this helps - anyone else help?
David