new to 5/10, turned two pair

[cliff]

Live 5/10 at a local cardroom. This is my first shot at this level, moving up from lower stakes, I apalogize in advance if this hand is boring. The game is fairly short, 5 players, two of whom were slumming because there was no 10/20 running. The game had a lot of action (typical, made a bit more so by the higher stakes players).

Preflop:
hero $280
SB ~$300
CO ~$900

hero is on the buttom and is dealt A2 offsuit. Folds to CO, who calls, as does hero, SB raises to $40. CO and I call.

This was by far a standard raise, and I did not take it to indicate any strength, as the player was bored and was raising everything. CO is fairly loose, and in my experience (from playing him occasionally at lower limits) is good, but really enjoys gambling with a wide range.

flop: (I don't remember suits, but they did not factor) J62 rainbow.

SB bets $50
CO call
hero call

As I said, I did not fear SB at this point (he will always CB) as he would likely push with any real strength since the CO was calling a allins with speculative draws.
thoughts?

turn: A
SB bets $50
CO calls
hero calls

CO says at this point that someone probably has two pair already. I thought he likely had an A, but thought a J was possible with a hope of making two pair or better on the river.

thoughts?

River: Q (not completing any flush draws)
SB: bets $50
CO thinks for a while and then pushes, which was my plan.

hero?

I'm pretty sure I played every street badly, at least the turn.

I was, however, confident that the SB was not calling behind me if I called.

thanks.

btw, this is my first hand post, hopefully I covered the basic format. Like I said, I don't recall the suits, because flush draws never seriously entered the picture.