The villain is a totally unknown player.
Today I played really well but in this hand, even after my analysis, there are more questions than answers.

Preflop I don't like to 4bet and it's my standard call on BU. Let's see a flop.

I flopped what I wanted but I was confused about his sizing because he is just screaming 3 barrels here. The problem is that we are deep, but I cannot raise and a fold is not an option too, so I have to call I guess.

He was thinking for a few seconds and then he decided to bet $2,50 and I had a mindfuck.
After my call the pot would be $10,24 and he had $10 left so I had a tough decision because that means we could play here on whole stacks.
Calling a turn and folding a blank river wasn't a good idea but I felt that I am behind.
I entered a tank mode and decided to fold because I didn't know what to do and my timebank was only 20 seconds (thank you pokerstars for decreasing a timebank ffs).

After a session I thought about this spot for a while. He might have sth like AA/KK/QQ/AK/AQ/KQ/flushes/sets/AsXx and I just cannot see any reasonable bluffs here other than flushdraws but still I got a feeling that I played really weak and I am curious about your opinion here.

As I said, I am very satisfied about my game today, but this hand is a fly in the ointment.
I even don't know if I played it wrong and I am pissed at myself haha.