Late period

So my period is about 5 days or so late. I am a little worried. I think I am not pregnant as the last time I had sex was a week before my last period. I got sick with the flu and bladder and kidney infection all together at the same time ugh a few days after my last period!!!! I took medication for flu tamiflu and bladder infection pills. Could this have delayed my period or what could be happening? I'm trying not to stress about it as I know that will make it even longer. Anyone have any ideas of what could be going on? Oh and I'm not on any birth control pills or anything just use condoms.