exertion headache

I'm worried about an intermittent intense throbbing head pain when I cough strenously, strain on the "potty" and position my neck a certain way. This started three weeks ago and now I am frightened that since I am stage IV that things have moved to my brain. I recently had a clear bone scan and a clear ct scan of pelvic and abdomen. My ca 15-3 tumor marker rises 6 points every two months and is now at 46. I feel like I can't catch a break from worrying about this. Instead of feeling good about the scans now I have this weird headache to worry about. And of course it starts after my oncology visit. Have those with brain mets had symptoms such as this?