Definitely see the doctor.
I'll throw my 25 cents in here. A few years ago I suffered repetative stress in the elbow and upper arm area. I was working full-time [ah, the days] as an editor, but working from home at a poorly setup workstation. One day, with very little preceeding trouble, I began suffering incredible pain while using the keyboard and mouse. Wound up seeing a doctor and being forbidden to use my arm for a month. No computer, no writing, no lifting ... horribly dull. After two months of recuperative rest, exercises, and frustration at not being able to do what I was used to doing, I went back to work with ergonomic improvements to my work area. The first thing I was told to do was scrap the mouse and get a track ball. Also put the keyboard on a lowered tray and adjusted the height of my tray, chair, and monitor into proper position for the least amount of strain.
Then there were the breaks; I never used to take them. Now I make a point to do so. I think that working at home was the source of many problems because when one is at an office, with other people pulling you away all the time, you takes breaks without thinking. At home, I would just work through and only get up to use the bathroom or eat/drink. The day I had the major problem, I had been transcribing for something like six hours without a real break. Now I know better.
With changes to my work area and habits, I have rarely had any problems since. Laptops are a real issue, though. Unless you have it connected to a proper ergonomic desk setup, just about any position you use it in is going to strain something. When I use it on the sofa [bad me] it's my back that suffers. I only do that for quick e-mail and simple computer work and try very hard to sit here at my desk like a good girl for most things.
[I'm with PeeDee on not being able to use those butterfly keyboards. I'm a glorified hunt-and-peck typist, and it's just too hard to do on that setup.]