imsoaddicted: I take it the pop you are referring to has caffeine in it? I had the same problem about 4 years ago and was told to get off the pop. I was drinking diet coke and about 3 litres ormore a day. the headaches lasted about 2 weeks ( withdrawl from the caffeine) Once you get through that the rest is a pie of cake ( bad pun for the diet board)
The difference once you ween off caffeine is amazing. I was getting migraines, huge pains in my neck and legs nearly every week. I no longer get migraines on a regular basis now that Im off it.
Hope that helps!

*to ween off, go from 2 litres to just 1 for about a week or so. Then cut that in half for another week. Unless you wanna go cold turkey like I did, but the other way the headaches may not be as bad.