Hello, For The Past 2 Weeks, Everything I Eat From

Hello, for the past 2 weeks, everything I eat from the smallest thing to a meal makes me bloated to the point I feel like my stomach will pop, in a week span of time I can no longer wear my belt on the second loop because it's too tight. So I've gained weight. I'm always tired. Today I smelled food that wasn't even in my house & my parents couldn't smell it. I'm a little bit more hungry than usual. I took a test yesterday that said negative. I've been on birth control since October and this hasn't happened before. I woke up and my whole back was aching. Breast are getting bigger. I don't know if it's the birth control or what :(