Chlamydia without sexual contact?

Recently, about a week ago, I was diagnosed with chlamydia. My first reaction was to tell my boyfriend, who I assumed gave it to me since we’d only started dating about two months ago, to get on some meds and get his cleared up as well. I sent him that email telling him (we’re physically apart at the moment), so he went and got tested, but his test came up negative.

Now, I haven’t cheated on him in any way, shape, or form, so I’m very confused as to why I have it, but he doesn’t. The only thing I can possibly think of is that I was drunk at a party about three weeks ago (after my boyfriend had left), and another girl, two guys, and I got into a hot tub. I’ve read conflicting information on whether or not you can get an STD from sharing a hot tub with others who might be infected, so I figured I’d ask you all as to what you think is going on here, as I’m REALLY confused and don’t want my boyfriend to break up with me over something I didn’t even do.