Can Vaginal Odor Be Due To Infection?

I noticed that I have a slight "tuna fish smell" from my vagina. There is no itching or discharge. Could this still be an infection of some sort? I showered and its still there, not strong but a light smell. I'm worried. I am currently on Prednisone for asthma problems. I have been for two weeks. I recently finished zithromax on Thursday for URI. Could the steroids have any affect on this? Please help I am very concerned. Thank you for your time.