can being sick affect your period?

I was sick for almost a week (fever, headaches, dizziness, drowsiness, very tired) right before my period was due. I felt normal again about a day or two before my period was due. my period came on time, but it was very very light, almost to the point of just spotting. it was also brownish black in colour. could this have been because I was sick? did it throw off my cycle? or is there a chance that it is implantation bleeding??