Can an illness cause a late period?

My period is 10 days late and I have bronchitis. I took a hpt at a week late with fmu and it was neg. My GP says I can't take my antibotics until I am sure. So my question is can an illness really cause a period to be delayed or should I keep testing. I am having no pms or pregnancy symptoms. I usually have really bad pms before my period though. So do you think I could be pregnant or is it the bronchitis?