What does it mean? 😣

On Monday I started taking contraceptive pills and since then I've been feeling a little bit off, I'm really tired, I'm nauseous and I have some headaches. Is it normal to have that during the first week of taking the pills? During this week I had a really light flow which is unusual for me plus me and my SO regularly have sex and we always use condoms and we are really cautious but now I'm worried due to those weird symptoms 😣