What Causes Spotting With No Regular Period Along With Sore Breasts?

my period was late by 10 days and i was dizzy, lost my appetite, moody and contripated, all i want to do is drink, but we took a pregnancy test in the evening on thursday and it was negative then i have had a little spotting on friday morning, then slightly more than spotting over the weekend, but it has been reddy pink and watery....no clots and no heavy flow and now it seems to have almost gone? Should i be worried? I normally have a very heavy first 3 days with back ache and very sore breasts but i have not had this....just slightly sore nipples....but i am still extremely constipated, moody and no appetite and i constantly have the feeling i am going to vomit....