Pinholes on Betta’s Tail?

[Z4D]

I discovered this 3 days ago and it’s only gotten worst. Water is cycled, ammonia/nitrite is 0 ppm, pH is 7.2 and nitrate is 5.0 ppm, his tank has Indian almond leaves and plants. He only has ghost shrimp in the tank. He just recently regained his appetite after his first treatment of ick. He is still being treated for ick and I don’t know how to treat these tiny holes on his fins. The photo in the cup was 2 days ago and today is the one in the tank. It was fairly hard to get any photos of his fins unclamped. It is more apparent on the very top. Any advice would be appreciated!

Update: there is a major increase in red blemish on his fins. I'm very worried.

 

[Naughts]

How did you treat the ich? This usually only occurs when you add new fish, how long have you had him?
do you do regular large water changes? i.e. 50-75% per week?
If you don't have meds in the water now, do a 75% water change with dechlorinated water. keep testing for water quality.
Hopefully someone else might be able to help diagnose the problem.