Headache is worst ever and too scared to tell my boss. Should I take any tablets?

Go to the ER. The description "worst headache ever" often goes with a subarachnoid bleed, which is potentially fatal. This requires going to the er right now to rule this out with a ct scan. Just tell your boss you need to go to the er and go!
No. If you are truly experiencing the worst headache in your life, tell your boss and have someone drive you to the nearest hospital. I dont know what kind of tablets you have so i can't advise you. It would be better to have a physician evaluate you before taking anything. A "worst headache ever" should be taken seriously.