One of my first few hands in 200NL

[rikz]

Once he pops your check raise to $50, I think he's announcing that he's not going anywhere. You don't really have pot odds or implied odds to just call since if your flush hits on the turn, then villain might fold out to any decent bet, and if a flush misses, then villain could very well push the turn.

So, it's push or fold, I think. Pushing is good if you have reason to suspect you have a decent amount of fold equity. My experience is that semi-bluffing a second time as a 4-bet all-in, especially after your check raise didn't scare villain at all, is not going to have much fold equity. So, giving villain credit for at least an overpair, you are a slight dog for all your money.

Holdem Hi: 990 enumerated boards containing 4s 9c 8c
cards win %win lose %lose tie %tie EV
Qc Tc 486 49.09 504 50.91 0 0.00 0.491
Js Jd 504 50.91 486 49.09 0 0.00 0.509

Against a set, you're worse,
Holdem Hi: 990 enumerated boards containing 4s 9c 8c
cards win %win lose %lose tie %tie EV
Qc Tc 344 34.75 646 65.25 0 0.00 0.347
9s 9d 646 65.25 344 34.75 0 0.00 0.653

Against 2-pair you're behind too
cards win %win lose %lose tie %tie EV
Qc Tc 452 45.66 538 54.34 0 0.00 0.457
9s 8d 538 54.34 452 45.66 0 0.00 0.543

Given all these likely hands, wouldn't folding be better than pushing when villain bumps your check raise up to $50?