What Causes Light Menstrual Bleeding Along With Throat Infection?

Hi i had this light blood spotting this is the day that i should have my period.but my concern is last month i got few blood in my period 3 days normally light period only means not more blood came. This month i got fever as my troat has an infection i take antibiotic ang more medicines for 5 days during my fever i got spotting because this is the day of my period.but blood only coming when i pee. I become night shift 3 months ago until now im doing same and i drive 3 hrs.per day going to work. When i become night shift 43 days before i get my period.i become abnormal in my period. My period become light. Is it normal? Im 28 years old ang having 69kg weight. 5 4 in height. Thank you