My only read on the BB is that he'll call down with any pair. Did I slow down too early? how should I have played this?

Poker Room skin
Limit Holdem Ring game
10 players

Pre-flop: (10 players) Hero is MP1 with
3 folds, Hero calls, MP2 folds, MP3 raises, 3 folds, BB calls, Hero calls.

Flop: (6.5SB, 3 players)
BB bets, Hero raises, MP3 folds, BB 3-bets, Hero caps, BB calls.

Turn: (7.25BB, 2 players)
BB bets, Hero calls.

River: (9.25BB, 2 players)
BB bets, Hero calls.

Results:
Final pot: 11.25BB
BB shows JS10C
Hero shows JC QS

I'm not sure why I went into calldown mode, I thought maybe he flopped a boat for some reason.