Same batch but half is infected

So I brewed a cream ale and a regular porter.

Bottled everything using the same bottles, equipment, etc. I gave half to my brewing partner and I took the other half. Drank a few beers during the first couple weeks and everything tasted great. In fact, the porter took 3rd place at a recent contest. A few weeks later I think I have a infection in both beers. It's really hard to describe, the beer looks great but it smells really bad. The nose is absolutely horrible and it almost tastes like smells. The problem is that my buddy who took the other half, he does not have this problem. So my biggest question is: Why the hell did this happen. Then, does anyone know what the infection is?

I bottle conditioned the beers, once they were done I just stored them at room temp. My buddy took his home and did the same thing.

Did you bottle condition the beers at a higher-than-room temperature. If you're bottle conditioning temperature was higher than your buddy's, not only would it have carbonated more quickly, but any infection would have grown faster. Your buddy may be in for a surprise in a few weeks.

If the ONLY difference is the bottle conditioning temperature, I would have to guess it's the culprit. Especially, if he has stored his at cooler temps after conditioning.

they were all bottle conditioned at the same temp, after they were conditioned is when I gave him his half

How many bottles have you opened like this? The bottles are always a variable, too. Have you picked a pretty random sample of bottles (i.e., not bottles which were filled one after another)? How many has your buddy opened?