So, I've Had Really Bad Stomach Pains And Cramps For

So, I've had really bad stomach pains and cramps for the good part of the day, I put it down to just recently starting my period, I haven't been going to the toilet properly and have been blocked up for a few days, but I've managed to go and the first lot I had was drown with dark stringy lines in it and now my stool is very dark, watery and smells sweetish, I am still in a lot of discomfort and pain. Is it a health problem? Or nothing?