5 day late period followed by a 5 day light flow

I am usually a very heavy bleeder and experinice severe cramps. y periods are always 28 days apart. MY last reg. period was 12/08/08 my next period was to begin 1/4/09 i had slight cramping from 1/1/09 until 1/12/09. on 1/4/09 i had spotting and i put on a pad and when i woke up the following morning no blood, i had really watery white dischage which continued until 1/7/08 and then i began to have a brown discharge on 1/8/09 i began to bleed with no severe cramps just the same light ones i had been getting since the first of the month. i have been bleeding for 5 days but that is also light and watery, it has not been any of theusual pain. i took a hpt on 1/7.09but it was neg. so im not sure whats going on plz help