Exercise lots and eating healthier but still gaining weight?

I'm going on vacation and really want to look and feel good during it! I can't remember the last time I went a day without worrying about my weight and how I look. I'm 18 and I love running and can run an easy 7 miles any day, no problem and at an 8 minute average pace. I have been eating healthier, I never eat junk food and I worry about what I eat, never fast food or candy or soda. I'm 5'9" and weighed 132 pounds in February. I'm now up to 142 and I feel horrible. I haven't done anything difference since then, just run outside more instead of the gym everyday. I can tell that my body just looks bigger than normal and I don't feel like I've gained muscle, especially when I run distance, but now my thighs and calves look constantly "bloated"ish and if I don't stick my stomach in, it pops out big time. I'm going with friends on vacation for my graduation present and really don't want to worry about my weight and what I eat! What can I do?! I feel like my body is just used to my constant exercise like running or the elliptical or treadmill or bike at the gym so it doesn't lose the weight, I don't know.
Help!