I no longer do any sort of tricep extension exercises like overhead DBs, laying EZ bar extensions, and so on as they always aggravate my elbows. I just stick with dips, close grip bench, and cable press down variations. I ran into the same problem as you eventually, couldn't go heavy enough without causing discomfort.
I've tried all sorts of elbow placement and angles; and nothing seemed to help. I feel I still get the same results without using those movements and it has not dampened my progress if that helps any.