5 weeks and cramping maybe spotting

So I'll be 5 weeks tomorrow and I'm feeling cramps well I've been having cramps since AF was due but I heard that the uterus stretches and gets ready to support baby so I didn't worry much until today when I had strong cramps in the left side i went to the bathroom and the cramping stopped but I noticed really light red hint of coloring on the paper and then later it was a darker brown should I be worried no cramping now though