Can quinine water or tonic water cause headaches?

I have stopped drinking alcohol for over 20 months (wasn't a regular drinker previously) but I have to go into pubs for meals, etc.. So for the last 20 months I drink tonic water with my pub meal. However, I find that EVERY time I drink 2 or more tonic waters I get a headache akin to a hangover (main reason I stopped alcohol) the next day. I definitely think there is a connection as it happens EVERY time and I would like an explanation.