My hands are getting kinked

I've been working on knitting a Harry Potter Hufflepuff house scarf for the last two weeks....on and off. I'm sure if I really dedicated myself to it, it would have been done before now.
It started when I realized Harry Potter and the Half Blood Prince was coming out on the 15th...My goal was to make a scarf and be able to wear it for the movie when I went. I have yet to go see the movie, thank goodness.
I actually bought double pointed needles at Daiso when I went last, thinking I could use them for just this. Then I started the scarf (in Gryffindor colours), on those. The I realized the needles were waaaaay to long for what I was doing. And if I continued doing it on those needles, I'd have a very wide scarf.
So, instead of waiting to go back to Daiso to see if the shorter circulars they had would be short enough, I went to Michaels and bought the only short needles they had.(really, the only short one! Everything else was really long!) Instead of spending $2, I ended up spending $10. That hurt.
However, I must say, I really love them. I got bamboo ones (the bamboo ones were the only ones short enough.) - and I really like how they knit. The ones I got at Daiso are also bamboo, so it wasn't a surprise, but it did make the $10 a little easier to bear.

I've gotten 6 out of 19 stripes done now. After every two stripes or so my hands start to hurt in the knuckles. Anyone know any good ways to keep your hands from cramping and hurting while knitting for long periods?