I Have Had A Sore Elbow For " No Reason"

I have had a sore elbow for " no reason" for a couple of weeks. Can't tell if it's the muscle or "funny bone" itself but it bothers me much of the day. The area is not swollen nor does it appear different from my other elbow. I am very active but didn't injure this elbow. I am not overweight either . 5' 6" 118 lb No other health issues.