Headache for 3 days?

So weirdly enough I've had a pretty moderate headache for 3 days now with little relief. It was at its worst yesterday, the pressure was almost unbearable and I had to stay in bed for a few hours. The only thing that works temporarily is Tylenol but it keeps coming back once the Tylenol wears off. I'm really stressed out, and this is just adding to the stress. It's pressure on the sides and back of my head, and a bit in the front as well. I rarely get headaches so I don't know what's up. I'm a total hypochondriac so I'm a little worried about serious things like meningitis (even though I got the vaccine twice and don't have a fever as far as I know) and also worried about some kind of serious infection as I have two rotted teeth in my mouth (long story) that can't be extracted for another month or so. This may sound kind of stupid but I'm also worried about brain swelling as well because the pressure is so intense. Help? :(