Left sided pain in uterus, brown spotting, signs of pregnancy?

For the past week or 2 I have had pain in the left side of my uterus, sometimes sharp, other times a dull intermittent ache...the pain is very different from period cramps however and is very noticeable the past few days. At first I thought I might have a cyst, but I have also been having a brown spotting for the past week or so. I am concerned that these could be implantation symptoms, especially as I have been very fatigued and have headaches out of nowhere and just don't feel right. I have had breakthrough bleeding before but this spotting and pain is different. Does this sound like pregnancy to you guys or something else?? I don't know if I should take a test or just go to my doctor.