I'm sorry, but there is no way to know for sure, since the sex was only 5 days apart and pulling out doesn't work, and Plan B has a one-in-eight chance of not working. A couple of the clues you have tend to suggest the first guy, and maybe one suggests the second, but none of the medical evidence is strong enough to guarantee one guy over the other. Do both guys know what happened? If so, could the three of you pitch in to buy a pre-natal DNA test from Ravgen or the DDC? It's a lot cheaper to do a DNA test when the baby comes, but if you could do it earlier everyone would know and could prepare.