Where did this weight come from?

Sorry for the length of this.Ok I'm an 18 year old male, 6ft even and 2-3 weeks ago I weighed 165 1/2. I went to my recruiter today and now I'm up to 171.Now during this time I wasnt sitting on my ***. I was competing in my D.E.P. Competition all day.Also I've been doing push-ups and lifting weights in 90-100 heat.(hot as f**** here in texas).And on some work outs I would run for a good five mins.Heck my jeans feel the same as they did when i was 164.Now I'm supposed to leave for basic on the 11th of July and I really don't need this.So can y'all help with a lil insight on what's going on here? Please and thank you