Frustrated that I'm gaining weight instead of losing!

Hi there,

I do clean eating, I follow the workouts, and am putting on weight. I decided to do some research on how nutrition is really more important and exercise can have the opposite effect(cause you to gain weight), and certain workouts(such as HIIT), can increase the stress chemical in your body leading to weight gain. But, I've been trying to disregard that and workout! I'm pushing 140 at 5'2 and at the beginning of this month before working out I was 129. Less than a month I gained so much weight, there's no way that's all muscle. Help!