Please Help- My period has come 2 weeks early??!

Hi ladies, can anyone give me some advice on why I have got my period again after only 2 weeks.
I had it from sept 24th til 29th, and i just got home from shopping, went to the loo, and wiped myself to find a very dark brown stringy mucus stand followed by what appears to be a period. (medium ammount of blood when i wipe)
I have been on the pill, but ran out on friday, so have missed a few days. I had unprotected sex on friday afternoon, planning to go to doctors and get my pill and catch up over the weekend, but i ended up being distracted with a family matter, and now (monday) ive got a period again.

Is it because ive missed the pill. Should i start taking it now, or do i need to let the period run?
I did a preg test yesterday, cause i was worried, but it was negative.

any advice is greatly appreciated!!

I would say it's because you've gone a number if days without the pill. When you stop taking it you can get your period... Wait until it's finished and start the pill again

It will be because you missed your pill a cpl days in a row! Don't stress but do take other precautions if you're not TTC!

Thanks so much, I feel somewhat at ease now. I was worrying, cause ive never had anything like this happen. How long will it run for? will it be a full period?

Yep more than likely a full period