Concerned about my betta

Question
Hi David-
Im not sure you can help with bettas but I thought I'd try. My bettas name is Bubbles and Ive had him for about 5-6 months. He lives in about a 1.5 gallon bowl with a small layer of rocks and a live plant. (Ive never had a heater for the bowl) He has always been very happy- swimming around a lot, playing at the surface blowing bubbles (hence his name). I usually do a full water change every week and a half and a 25% change in between. The only problem Ive had with him is that he is a picky eater. He doesnt like to eat pellets or flakes, only freeze dried bloodworms.
Well about 1.5 weeks ago I went out of town and went to the petstore to get some ideas on what to do for him whil I was going to be gone and they reccomended these tablets that you place in the water and it feeds your fish while your gone. So I got them and placed one in there the morning that we left and when I came back he didnt seem too well. Also, the water was very slimey looking at the surface and the water stunk REALLY bad. So I changed the water 100% right away and he seemed to do a little better and ate a little bit. When I changed the water I took the plant out and threw it away because it was really slimey and gross and I didnt want to put it back in there. So he went without a plant for about 4 days. Well he has been very lethargic and staying at the bottom of the bowl (sometimes hes laying on his side) and hes not moving very much and not eating at all- no matter what I put in there. I thought maybe it was because the plant wasnt in there but since I have put the plant in hes still acting the same way, now just hiding in the plant. Occasionally he will come to the top and stick his nose out but he moves really fast when he does and it almost looks like hes twitching. He will then immediately go back to the bottom. Before these problems started occuring he could recognize the food container and he was start swimming around and getting excited when he would see it, now when I pull it out he doesnt even move let alone come to the surface. Ive also tried putting some pellets back in just to see but nothing happens.
He looks fine physically- his skin looks good and his color is great. Maybe his eyes are a little bigger but Im not sure.
Do you have any suggestions? I'd really appreciate any help you could give! Thanks so much!
~Traci

Answer
Betta are the weirdest fish... I love mine to pieces... He may be sick from the nasty water... so I would do yet another water change and see if that perks him up.  The other idea I had is live brine shrimp... nothing makes a betta happier then hunting food.  try the live food and if that doesn't work let me know... dave