I'm a platinum player Zerg and I have one huge problem with ZvT. If a terran manages to sneak expand somewhere on the map and build a planetary fortress and surround it with turrets, it's very hard to react. Even more so if the expansion is in another main with a ramp/choke.
A PF with repairing SCV:s can withstand a ridiculous amounts zerglings/rouaches and same against mutas if turret repairing is done right.
Then the terran can just rest with his tank army and as soon as you try to take the PF down by brute force, he kills your main/natural.
The only ways I can deal with this is to go Broodlords or out expand my opponent, but it feels like there must be a better reaction to this.
Anyone has any clever ideas to deal with such situations?