My Betta :-(

Question
I'm worried about my betta, he used to be energetic and swim like a champ, the past 2 days he's been literally laying on top of the gravel on the bottom and bearly moving at all.  I tap on the glass to make sure he's still alive and he sometimes doesnt respond, other times he'll swim a quick lap then go back to the same spot and lay down again.  I just changed the water today and he's still doing it.  He's never done this before, he doesnt look good and i'm worried, PLEASE HELP! Thank you!!

Answer
What size tank/bowl? How often do you change the water?  Do you change all the water, or just a percentage?  Does he show any other signs of illness?  Is he looking a little fat?  This info would help to solve the problem.  Get back to me with a follow up.