No period, been sick, and negative test.

I am just looking for advice and information from anyone that has experienced this. Last month (end of February) I had influenza A for a week. A week ago Thursday I got sick again with a head cold. I was supposed to have my period over a week ago, so I waited and still nothing. Today I tested and it is negative. Can being sick a few times and having a hut to your immune system cause a missed period? Thank you in advance for input.