Should I be worried?

Ashleigh • My husband and I were happily married on March 1, 2014. We just found out we're expecting our first baby to be born around February 17, 2016. This is such a surprise and a blessing!
I am 5w2d pregnant with my first and I have had some very mild cramping and lower back pain. Today after using the restroom, I wiped and noticed a very small spot of bright red blood, smaller than that of a finger prick. I'm unsure if I should be worried about this or not? Help!