You are playing with an unfamiliar but expert partner. You are playing 4 card majors and a strong NT. You do not have many agreements.
The 1NT by partner was non-forcing. You decide to venture a takeout double after 2♥ and partner doubles 3♥.
What now?

Help

1♠ - (P) - 1NT - (2♥)
X - (3♥) - X - (P)
?