Sick betta, torn tail, open operculum,bottom of tank, help

[Ephy]

Hi i need some advice, please i am so worried about my betta.

For about a week i noticed he's not himself. He is always full of energy, but lately he's been resting at the bottom of his tank a lot. He's been resting under his normal cup he sleeps in, or tucked under other things in the smallest nook he can get into which i've never seen him do before.

Also, every once in awhile he will suddenly burst swim as if frantic or afraid of something. Never seen him do that either.
He's been having problem with his tail, it will look ripped one day..then it will grow back then for some reason i will seebits been ripped again. Ive taken out all of the sharp objects, even his filter because he use to squeeze behind it and i was worried thats what caused it.
But now..i noticed today one side of his operculum looks torn or ripped exposing the gill underneath.

I am so worried. I dont want to lose him. He still eats and seems really hungry but i am worried ive been over feeding him.

He has a heater and an air hose. Ive been doing full water changes the last 3 times thinking his tank must be in bad shape without a filter but last week i was late changing his water by about 4 days. (I usually do it every 7 days) hes in a 10G tank.

Also, because im dumb i realized with thr new water conditioner i bought i was measuring his conditioner wrong and doubling the dose!!

The last 2 water changes i cut the dose to the normally 10ml per 10G and he seems worse now!

I really messed up. I dont know what to so, please help??

Cant post pictures or video for some reason its not working, [emoji36]

 

[Ephy]

Here is a picture

 

[Ephy]

I changed out his water again and checked the water using my water kit i forgot i had.
Ammonia,nitrite and nitrates are all at zero. I'm starting to wonder if the nitrite or nitrate was too high. Since i wasnt able to change out his water as often as needed, it must have made him sick. I feel horrible about it.
I took out the sponge filter thing i made and just left the air hose in the tank as is. I also dropped in half an almond leaf in his tank.
I stopped feeding him his regular food and gave him a sma pea this morning. Tank temps are at about 78.
He seems more active than he was, swimming around more and coming to greet me rather than hiding at the bottom of his tank for long periods.
I really hope he is going to get better, i love that little fish!
This morning i noticed a small white thing hanging from his head. I've NEVER seen anything like this before and tried to take a picture...does this look like a parasite????
When i dropped in a piece of pea, he attacked it vigorously and the white thing came off...is it a parasite or just tank debris?
I havent seen anything else like it since but i will keep looking.