I understand your problem and will try to answer your queries to the best possible. There s no reason to worry. The bleeding you are experiencing is due to your periods. The symptoms that you are describing suggestive of pregnancy may not indicate so since sometimes delay in periods would also present with back cramping, headaches, tiredness. Since you have also taken the home pregnancy test and the result is negative there is no reason to panic. The bleeding may vary in quantity, which is normal. I would suggest you to wait and watch for the next periods and if you experience similar symptoms then you can consult your obg-gyn doctor. You can also use an painkiller to relieve the pain.