First and foremost, I'm not really a fan of letting people know what im laying down. I guess thats something up for debate, but I don't think you want to be showing laying down hands like that in situations like that. If your opponent has any sense he'll try to expose you for laying down good hands to pot max bluffs on the river. I think its better you have him thinking you layed down a pair of queens rather than that, but maybe I'm overthinking that particular omaha level. Just my take.
As far as the hand, i'm kinda of confused how you laid it out, but I think I got it. oop your bet was kind of weak, and the middle player couldve took that as a sign to make a move. I can't really fault you for laying down on the river because you've got a middle position player betting pot max on a paired board with no regard to the person on the button turn and river 2 straight bets. Plus on top of that he's playing like he doesn't even care what you have. So I'm not saying I would've folded there myself I dont know what I wouldve did if I put my self in that particular situation, thing is you make sure u don't put yourself in those positions next time.
Its hard most of the time to control the pot OOP in omaha for numerous reasons, but this was a hand where you had a sweet chance to control the pot. I really don't have a problem with your flop bet I'm thinking you wanted to show weakness maybe, no problem with that. After the weak bet on the flop no problem with the check on the turn I was thinking you were looking for a bet for someone else to steal the pot, THATS WHAT YOU GOT, what you did wrong in this hand is you didn't check raise on the turn. You got a chance to possibly commit 2 Other players to the pot before they even get to see the river card with a pot max check raise right there and thats where I think you messed up.
It don't matter whether the 3rd 9 comes on the river or not, I think at those stakes, playing OOP you wanna get your money in on that turn, because you don't know what the other players are gonna do YOUR OOP. The villain may be calling regardless of your raise, and the button player is probably gonna be more inclined to call a raise on the turn than to call a bet on the river when he misses, plus it seems like they've already written you off in this hand, you gotta check raise that turn man with that hand. To maximize profits because you got the chance of potentially committing 2 people to that pot and there gonna probably call on that level
If you check the turn and say they didn't bet than the pot wouldve been more manageable for you to call the river regardless of what card comes if u dont wanna bet. Remember, you gotta protect your hand, I know that hand seems super nice and it is on the turn, but it aint only a 3rd 9 you got to worry about, if you got any of those players being on over pairs your letting them control how much they get to pay to check the river for their overcard full to pretty much obliterate your hand if they hit, cus you may have folded to that 3rd 9, but you aint folding to someone hitting a higher over set on the river.
Last note on the river, the river call basically is gonna be based on your reads on that player cus that oop aggression aint necessarily an easy call to make given how he's betting. If you aint got no reads thats a tough one if your bankroll is right and its a player your gonna be playing with thats a hand you could test him on to see. If he's generally someone who bets pot thats def more grounds to test him out, because alot of time people bet pot thinking Im only gonna get raised by the nuts damn near, and only marginal hands to what my hand will call me which if they call I could have beat. or it could just be an outright bluff. If you don't think you can call a bluff on the river, than you might want to bet yourself there to see if he'll respect your bet.
CHECK RAISE THE TURN IS WHAT YOU TAKE FROM THIS!