Sick (??) Betta

Question
My son's betta used to be a nice red color with some blue and green.  Now his color seems to be disappearing.  In addition, he seems quite listless -- his fins and tail are not flowing.  He seems almost compact and is mostly at the top of the tank.  He does not like the betta pellets and only eats dried bloodworms (we give him about four per day.  His appetite has not been good since Sunday.

I would think that his relative inactivity is related to the recent cold weather, but my other son's crowntail is acting fairly normal.  We changed his water only four days ago, so it's not that either.  (He's in a one gallon tank with a lid.)  

He doesn't seem to have white spots, except for one near his jaw that he's always had. Any thoughts?

Answer
It does sound like it is meerly that he is too cold. Bettas do come from tropical climates and need a higher temperature than most fish. What temperature you have now? I would suggest 82-83F too keep the betta and the other fish happy.
If this does not work, please contact me again at megan140@msn.com with a picture of the betta (is possible)