...that it sounds like a upper respiratory infection - in fact, with smaller snakes I often see that little jerky-like action to cough up any mucus they may have in their lungs, etc. It looks different - at least to me - than when they are 3' or more in length and have some girth on them.
Like Jeff said, check the temps. and provide only minimal water - Jeff suggested in the hand which is good...I usually give them a sanitized bowl that they cannot in anyway fit into but can drink from. I would also (I don't know what substrate you're using) clean the cage with at least an anti-bacterial soap and then line the cage with paper towels or something similar. Also, take any hide boxes and any other item out of the cage and maybe drape a cloth over the warm end to keep the cage covered (but not the airflow!) so the snake will feel secure. What kind of cage do you have - sometimes a cage will allow too much airflow and it makes for drafty conditions; the snake has no where to go and that can create medical problems for you too.
The good news is that if you haven't noticed any gaping, mucus in the mouth, or bubbling at the nostrils then you've probably caught it early or your snake is healthy enough at this point to fend it off. If the snake is sick with a respiratory infection, you can't act quickly enough - probably the number one killer of captive bred kings, or at least it is as a secondary response to another medical condition.
You can also go to a vet. Most vets that work with herps like to see them and are pretty cool with the fees (they see SO many cats and dogs!) and an shot for the infection and a clean cage should do the trick for you.
Good luck!
-John