Can IBS flare ups cause light periods?

[Abirose25]

Is it possible for an IBS flare up to affect the menstrual cycle (rather than the other way round)? Often, when I have an IBS flare up it will coincide with my period and make it more painful. However I began to experience the symptoms of a flare up around 3.5 weeks ago when I started getting bad stomach cramps, bad stomach bloating (which several people have even noticed and pointed out to me, which hasn't happened before), alternating bouts of constipation and diarrhoea and several lbs of weight gain. About 1.5 weeks ago I was due to come on my period - I experienced light bleeding for 2 days with very few period cramps (unusual anyway, but highly unusual during an IBS flare up) and then it stopped. I'm in a stable relationship and using contraception but took 2 pregnancy tests anyway to be safe and both came back negative. My question is could the two be related? Or is it possible that my bloating and digestive irregularities could be related to a hormonal issue (or even possibly the dreaded C-word) rather than IBS on this occasion? I don't know if it's relevant but I also began suffering from bad headaches that last anywhere from hours to days long around a month ago too... they were very bad in the days before I was due to come on my period but appear to have subsided a little since (I should probably also point out that I have just returned from a week long holiday and my diet was not ideal while I was away - I have no doubt that this may have contributed to some extent to my bloating and irregular bowel movements but doesn't alone explain why I look almost 6 months pregnant despite exercising, drinking plenty of water and eating lots of whole foods for the most part of the 3 weeks either side of my holiday...) I plan to go to my local surgery to get this investigated further but I'll be unable to go for at least the next week and wondered if anyone could narrow down the possibilities for me or at least offer some suggestions for relieving the bloating / discomfort?