[beachbum]

I think your best option here is to call.

I might 3-bet if he's the kind of player that will c/r a 4-flush or OESD. But here you've got no reads.

You can't fold because I think you have implied odds to call his c/r. You're getting 7:1 from the pot now. You have about 1 out each for your backdoor flush and straight draws respectively. Plus, you've got 2 outs to a 3. On average, if you make your hand you'll get paid off my more than the required 4 small bets to make this a +EV call. Even if it was a slightly -EV call, folding here shows weak-tightness and encourages him to take shots at you in future blind wars/steal attempts.