PokerStars No-Limit Hold'em, $1.00 BB (9 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

Button ($131.50)
Hero ($99)
BB ($36.20)
UTG ($104.15)
UTG+1 ($182.10)
MP1 ($165.70)
MP2 ($92.80)
MP3 ($94.50)
CO ($30.40)

Preflop: Hero is SB with K, Q.
7 folds, Hero raises to $3.25, BB calls $2.25.

Flop: ($6.50) 4, J, 4 (2 players)
Hero bets $5, BB raises to $10, Hero ???

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BB is a complete unknown.

What's your move here and your plan for future streets?