Could Delayed Periods Be Due To Cortisone Steroid Injection In Heel?

I have had a cortisone steroid injection in my heel for plantar fascitis. After a couple of weeks my period has been late for 12 days. I have a lot of symptoms for pregnancy (some which could be in my head, others which are more noticeable), but a I have had 7 negative home tests and 1 negative blood test. Could the injection have affected the results?