When to worry about a headache?

I've had a headache for a few days, keeps getting worse, Tylenol barely takes the edge off anymore...

I deal with migraines, but this is far worse than any headache I've ever had...

When ever I sit or stand up I start blacking out and feel like I'm going to pass out

it hurts so much I'm nauseous

when it is at its peak I can't even move my head it hurts so much

advice? ideas? tips?

I've been debating going to the er, but don't want to make a big deal out of something that may not be a big deal.