Hi My Period Was 5 Days Late. My Period Is

hi
my period was 5 days late. my period is always on time always. Got a blood test which was neg. i had a very very light period and now brown discharge. Ive been vomiting, had diarrhoea for 2 weeks, backaches, my nipples have been a darker colour. What should i do we have had unprotected sex 2 weeks before my period, and again 2 days before expected period, partner works away.