I am 21 and I started my first period on my 13th birthday. Unlike you though my first period was extremelly heavy. Over the last 8 yrs I have experienced brown black and even a little bit pink and white blood. I've went to all sorts of docs and finally at 16 they figured I had endometriosis. I have always had irregular periods. They also were always EXTREMLY PAINFUL! Its sounds like u are in the beging stages of your period. Its probably that your body is trying to start and you have old blood (the brown blobs). I had periods with only a 2 week intervil for about 6 months, talk about irritating. I understand what your going through and once your body understands what it needs to do you should start to become more regular. Also my doc recomended that I DO NOT where tampons unless I absolutly have too. My endometriosis is very painful even without my period so take into consideration that this could be a possibility. They only way that they know for sure is by a laproscopic procedure that is rather uncomfortable. I hope this helped in some way also drink milk you need calcium and try not to take to much of tylenol. I have found midol to be very useful until about a year after my surgary, of course though I do have endo.. so dont think that it couldn't help for you. Also stay active and exercise to help reduce painful periods (so my doc says.)