What Are The Side Effects Of Emergency Contraceptive Pills?

Hi, well I'm 19 and have been taking the contracpetive pill, Cilest for around a year now with absolutely no problems. However, I have been bleeding quite heavily for the past 6 days mi-way through one of my packets. This has never happened before. I did feel pre-menstrual cramps before I began the bleeding and the bleeding itself is akin to the periods I used to experience before going on the pill. I haven't missed any pills, have been very consistent in the time that I've taken them, haven't been ill or been sick and haven't been sexually active for a month. I am very concerned. The only possible explanation I myself can come with is that I have also started re-taking dida candida tablets which are supposed to aid bloating etc. I have taken them before with no problems but it was around the same time, possibly even the same day that I began re-taking the dida candida tablets and the bleeding beginning.