Ouch... sounds like that hurts.
I'm a loose knitter and usually use 0's for socks. I also knit continential... I know that for some, knitting continential helps to loosen up their stitches, you could give it a try. That or really force yourself to loosen your stitches (not easy when you are comfortable in your own knitting style)
You could also change needle style - I would recommend bamboo, however, if you knit tight, you might break them. You could try the Susan Bates - the yarn will slide, but they aren't as pointy as the addie's.
Worse case - you mentioned it, get a thimble. There are some really neat ones for quilters that only go onto the finger tip, so you don't lose mobility in your finger as you are working. They even have ones that stick in the tip of your finger. The leather ones will still allow some mobility in your finger, but will also protect it.
Good luck and I hope that you find something that works- it's no fun when you are getting stuck while working on a project.