Why did my phone stop writing to my SD card?

[Ed14]

5 months ago, I got a 30GB SD card for a LG Vigor phone. Everything worked great, but today apps like Rhapsody and Podcast Addict will no longer save to it. Everything that was previously on the phone works, and Netflix is on the SD card, and it works. However, anything new from apps, or my laptop will no longer be read from my phone. I heard that KitKat does not like to save to SD cards anymore, but it was working fine until this morning, and to my knowledge no updates were added. It just suddenly stopped working. Is the problem my SD card, or is it true that the KitKat system suddenly stops writing to the SD card from third party apps. It's a bummer, because without that SD card, very little can be stored on the 8GB phone. What do I do?