Weird thing on fin

I've notice a few times he has something tiny hanging on the very end of his fin and then later it'll be gone I guess from brushing on a plant or something. I've noticed it before but the other day it was way more noticeable.

The first two pictures are from the other day, the thing hanging on his fin almost looks clear?
Then it came off and it was there again today, that's the 3rd picture. What is it? He also still has some fin rot and no matter how much water changes with salt I do I can't get rid of it.
Any help is appreciated.

Just looks like coloration to me. His fins also look good. (My betta used to have a small white mark on his dorsal fin. It wouldn't go away. He was perfectly fine)

But I'm talking about the actual thing on the end of his fin, it's not part of his fin.

Excess mucous or a bit of fungus.

Add 2 heaped tablespoons of rock salt for every 20 litres of tank water. Keep the salt in there for 2 weeks and see how it looks. If there's no improvement after a couple of days with salt, post more pics.