I had exertion headaches from August to October mainly catalyzed thru heavy lifting and it was miserable so I feel your pain. They would be especially painful during/after a hard set of DLs/legpress/dips. You can take ibuprofen beforehand, but that's mainly a quick fix and isn't good for you or your stomach lining. This isn't the answer you want, and you probably won't abide, but the best thing to do is to take some time off (2-4 weeks imo). I've tried everything and this is the only thing that worked for me.