itching, tingling, stinging, burning in upper r arm

I had a bite of some kind about a year ago on my upper arm (deltoid -- in front of the tricep area) which triggered what I would call a histaminal itching and burning in the upper arm in a centric area around the bite, lasting for a couple of months (in waves of itching and buring each day) and eventually fading. Now, some months later, it has recurred with exactly the same sensation, an itchy burny feeling with a pinpoint centre as if the sting had happened again in exactly the same spot. What could this be. Why did it last so long. Why is it recurring in exactly the same fashion iwht almost the same sensitivity?