Hi. I Have Been Experiencing A Sticking Pain In My

Hi. I have been experiencing a sticking pain in my lower left abdomen. Also I am feeling a heaviness and tightness in that area. Sometime last week I also experienced some "spotting" just for about 2days then it stopped. I haven't seen my period as yet since I haven't been really tracking it. Can you tell me what could be the problem. Also I took a pregnancy test sometime lastweek and it was negative.