Hi again :)
glad you replied :D
Now we probably need to tackle some fundemental problems that have affected your fish over the past few months.
don't panic though, it might just be that he needs a heater.
You see, betta fish are tropical fish, who dont do all that well when the water hits lower than 70F. Their metabolism slows down making them prone to all kinds of problems that the immune system is too weak/slow to handle.
the ideal temperature for this species is in the 78-82F range. a little lower or higher is OK, as long as the temperature is kept constant.
for a 1 gallon bowl, I recommend a 25w adjustable heater. the hagen elites sold on amazon are great for their price. if you are a student you can get free 2 day shipping if you sign up... or you can simply piggy back the product and get free shipping when you hit the $26 mark.
if you dont have access to amazon, simply purchase a 25w adjustable heater :)
you are doing well on the water changes.
to make sure the ammonia build up doesn't harm your betta, it is highly recommended for 1 gallon, to do twowater changes weekly.
that is, a 50% half way through the week, and 100% at the end. This is a tested method that will ensure that keeps the water constantly safe for bettas.
This is another issue we will need to make some modifications to. Like people, betta fish needs a good balance of nutritions in their food. blood worms unfortunately are not very nutritionally balanced. I highly recommend to make switch over to pellet food. good brans include, omega one, new life spectrum, hikari(who recently brought back the old formula) and attison pro.
the blood worms can be fed once a week as a treat instead of his regular meal :)
The recommended feeding schedule is 2 pellets, twice a day.