Is tension in the lower abdomen an adverse reaction of Vines, or could it mean something worse?

Good morning! I have been taking vines birth control pills for 6 days. I started taking them on the first day of menstruation (20.08.2021) and I feel a slight tension in my abdomen. It's not pain, but discomfort that worries me a little bit. I wanted to ask if this is just an undesirable effect or if it can mean something worse, like poorly chosen pills. Before I started contraception, I was at the gynecologist and everything was fine, so I don't think it was anything unrelated to the pills.