Unexplained weight gain.. What's going on?!

Jaclyn • Realtor. Wifey. Lucky Lady.
I'm 26, my normal weight is between 155-160 & I am 5'8. Looking for some input and if I should go to the doctor?
Around July, I started taking bc pills. This may have played a factor in my weight gain but I only took it about a month or so.. Just wasn't for me. 
In August, I went on vacation and didn't really work out again until late Sept. In August, I was my normal weight of 160ish. I now excercise an avg of 2 days/week, & just started taking Zumba.
It seems that every week I gain a little more weight. Im now 185 lbs! I've never been nearly this heavy and I've never gained weight so fast.. I didn't change my eating habits, either. I don't eat that healthy, but not that bad either, to gain over 25 lbs in a short period of time.  
I was wondering if I should try personal training or go to my doc? I don't have insurance though so I would have to pay either way. I just don't wanna pay to go to my doctor for nothing... If there is anything out there for me to help aid in my weight loss to get my body back I would try anything.