6 week periods

Hi everyone is this right to post in here? 

I was just wondering if someone could help me or give me some information. 
I'm 17 and has my period about 7 years now, they are normally so regular 5 days every month no problem, but I've had this period for 6/7 weeks now with really painful cramps sickness and just not feeling so good. 
I don't really know what to do should I contact my GP? Is this normal? 
thanks in advance