Gaining weight or pregnancy?

Since about 4 days ago I had a sudden feeling like I had gained a lot of weight... not so much bloated but weight. I feel like its in my stomach and face. I started a desk job so part of me thinks it might just be the sitting catching up to me but also a possibly an early sign of pregnancy, because it was such a sudden feeling (rather than gradual weight gain). I’m supposed to start tomorrow.

Thoughts?