Sorry if this is too much information, but I thought I'd write anything down that might possibly be relevant. Thanks for your help in advance!

I've had brown blood for my period for four/five days, and now it seems my actual periods (red blood) is just starting. What exactly is "old blood"? And could this be old blood right at the start of my period?

My period was due probably Tuesday/Wednesday, but a few days later is nothing out of the ordinary. I got my period on Friday mid morning - I had inserted the menstrual cup early friday morning so as to avoid any accidents at my graduation and so didn't know until around midday when I emptied the cup. I took neurofen on Thursday afternoon and Friday morning as I was feeling cramps. Friday night I emptied the cup again and noticed the menstrual blood was browner and more watery than usual. I thought nothing of it as my period has just started. I continue to use the menstrual cup, emptying it 2-3 times a day as usual, and the blood is still fairly brown and not as thick as usual. Tuesday night, my menstrual blood was looking a whole lot redder and the cramps came again - I never get cramps in the middle of my period. I've no idea what my body's doing! Wednesday (today) my period is heavier and normal-looking in colour (dark red) - similar flow to what I would get on the 2nd day of my period.

My period usually lasts 6 or 7 days, but becomes much lighter towards the end. I've been using the menstrual cup for a couple of months now and it works really great - I've had no trouble with it. I'm seventeen. I'm a virgin, and I'm not on any kind of medication or birth control. I eat right and am only slightly overweight. No other symptoms other than cramps.

Should I talk to my mum or see a doctor?