Well my routines at the moment all start with squat and its been coming on probably about 4th or 5th set of squats and then stays till about 1-2 hours after I've finished. But its also happening whenever I do other strenuous things like throwing my 2 year old in the air etc so its definitely linked to activity. I had similar pains ages ago, before I lifted, after I'd over done it in the garden lifting sand and cement but it went away after a few weeks (and I wasn't lifting then so was easy to rest) - I thought at the time it was just overuse but reading up on internet (prob the worst thing you can do), it seems a trapped or compressed nerve could be a culprit.
Couple of years ago now but I used to get shooting pain in my arm. Down the forearm, elbow and sometimes up to the bicep. Started after about 6 month of weight training and it happened on pulling movements and sometimes when sparring, my arm would be shaking. Usually cold water would take the pain away. Went to the GP and she said it was tendonitis. Hopefully you dont have it as it took ages to go away and it stopped me weight training. Only just starting back up now.