Implantation bleeding?

we have been trying for another baby after having miscarriage. A week today (next tuesday) I am due a period and today I have had very light spotting (pinkish) I have an elevated temp feel a little nausious and have been at all hours 2- 3 o clock in morning when normally I sleep fairly soundly. Also my periods are as regular as clockwork could these slight cramps and spotting be implantation or an early period I have done a test and its negative - I am not sure if there would be enough HCG in the body yet - thanks