Why am I constantly getting ill after I had flu shot?

51 years old. Had first flu shot ever about 8 months ago. Got fever and congestion within hours of flu shot. Since then I have had numerous cold sores on my mouth, along with bad colds and sore throats. I also had shingles one month ago, and now I have bronchitis. It used to be that I was rarely ill. Now I seem to be constantly sick. Was it the flu shot, or something else? This is getting really old.