Birth Control Blues (Help?!)

I've been having a great few weeks in terms of happiness and stability and general life-ness but over the last few days I've gone completely downhill. I started taking birth control pills (rigevidon) on Monday 20th and thinking about it, that seems to be where things started going south. Is it just a coincidence that I started the pills on the day my plans and thoughts took a turn or are these tablets doing something to my head? Thoughts and advice would be absolutely great.