I have had the most painful what felt very much like a contraction.
It felt like a stitch on my lower right hand side, got worse and worse and worse over about 2 mins, to the point I was doubled over and could not move at all and would normally have been convinced it was a contraction. It hurt so much i thought I was going to throw up.
Except, it stayed on my right hand side, and hurt like a mofo for a good 3 mins (might have been more, felt like forever).
And now, it smarts a little, sharp achey pain, and nothing on my left.
Was 15 mins ago and nothing again since.
So, can contractions occur on one side only? Tell me no, as I was hoping for a bit more of a build up to the pain!