Beta- lethargic, sinking to bottom of tank

Question
I've had my beta for about a year.  I keep him in a 10 gallon, filtered tank.  The tank is temperature controlled & I clean the water every other week.  

I travel quite a bit & it seems my mother has overfed him while she was feeding him for me.  In fact, I know she overfed him last time as evidenced by the many floating pellets in his tank. I followed (or tried to follow) some advice I found on here about feeding an over-fed (constipated?) beta a cooked frozen pea to flush him out.  Problem is: he won't eat it.  I am concerned about him having Swim Bladder Disease which I read about here, but don't know what next steps I could try.  He looks so miserable. Many thanks!

Answer
Rena,

When you say the tank temperature is controlled, what is the temperature of the water exactly? The temp will have a lot to do with him being lethargic. When their water gets too cold, they will stop swimming and often stop eating. As for the filter, Betta males do not like them nor do they need them. The 25% water changes have to be done once a week. When you say you clean the tank, are you dumping out all the water or just some? Here is the best way to feed the pea. Fast him for 2 days. On the third day cook a pea. When it has cooled, remove the shell. DO NOT feed him the shell because he cannot digest it. Cut it into small pieces and feed it to him. Then you will fast him again for 2 days. Remember, his stomach is the size of his eye and it is very easy to overfeed him.
Let me know what the water perimeters are and the temperature of the water.