Insane Weight gain. Guys please help?

Hi, I am a working girl and I have been facing weight issues from the past one year. I have never been a skinny person and used to be a bit fat but then I started working out in the gym daily for about 2 hours a day and reduced my weight by 12 kgs and became quite fit. But I never used to do any control on my diet and had normal food including junk food as well many a times. This was when I was a student. After I started working, I still used to go to the gym, but I started gaining weight. But the weight gain was normal and not much. However last year I got chickenguinea and I left gym because of that. And then I rejoined gym about 3 months later. Since then weight gain has been increasing at a very fast pace, even though going to gym for 1 hr, 5-6 days a week. I have cut down on junk too. But still no results other than continuous weight increase. My mom has this thyroid thing and I think may be I have it too now but I don't really know whom to consult. Could you guys please help?