First cold sore ever at 27. To herpes?

Cold sore on corner of mouth/lip out of no where first ever, married same partner x 9 years-, had a cut on knee a 1.5 weeks ago - turned out to be prpbable tetanis - urgent care gave me the tetinus vaccine and prednisone pack- I have been taking one 20mg prednisone 3 x per week during April for wrist/arthritis pain vs taking my prescribed ty3 bc I wanted to only take ty 3 when absolutely necessary bc it stopped fully managing there pain after 3 years. And the prednisone will take the pain away for up to 6 months after I take it for 2/3 weeks ..AND I have a umbilical hernia (2 finger tips-having surg in june) so I am assuming my immune system isn't at its best.. So my question would be, Could a cold sore be unrelated to herpes ???