How would you of played?

[cheapseats]

I am playing a dollar micro 250 grt and at the blinds 100-50 I am dealt AQ of spades in the cutoff position. The first thing that I would like to point out is that in most cases players either don't know or don't care about position, but here it goes. It folds around to the player directly to my right and they limp, I have played one hand so far and we have been playing for about 30 minutes, so I raise it up to 450. It folds to small blind and they call and the big blind calls and the original limper folds. Flop comes 10 spades 5 spades and 3 hearts. The sb checks bb checks so I bet about pot size, 1200 and pot was 1450. Sb folds and BB reraises me all in. I am thinking that he either hit his ten or is trying to push me off the hand so I call and he flips Q5 off suit and knocks me out with a pair of fives. How would you have played the hand and maybe someone could tell me what the Q5 was doing in the first place calling, was it priced right to see a flop and why 3 bet all in with bottom pair. Maybe its just me but I seem to lose against hands like this all the time and I think that I play and bet the right amounts to weed these fish out but maybe I just have to start shoven from the get go. Please share and thanks for the response.