What would cause my microSDHC card to refuse to add/delete anything?

I got an SD card for my phone, for storing pictures/videos (and to easily get them onto my computer). It acted fine for a few weeks, but now it’s refusing to cooperate.

If I delete anything from the card (Whether it’s connected to my PC, or to my phone), it will get deleted. But if I then pull the card out and plug it back in (Either to the PC or to the phone), the deleted things will return.
If I save anything to the card from the PC, it’ll show that it properly saved. But if I then remove the card and plug it back in (To PC or phone), that new thing will be gone.
If I try to save anything to the card from my phone, it’ll just save as a broken image. If I try to transfer that broken image from SD card to internal memory, it will give me “Invalid filename” error.

I can still properly save (and txt/email) photos if I set it to save to my internal memory, but then if I try to transfer that to the card, it will get saved as the broken image.

So long story short, the card likes what it has on it, and doesn’t want to change for any reason. And that’s kind of problematic.
I’m not rough with my phone, I haven’t dropped it, I don’t expose it to extreme temperatures or sunlight (There’s a nerd joke here, but I can’t be bothered), I haven’t had it go swimming in the toilet. I’ve been good to my phone and the card.
And it’s pretty clear to me that it’s an issue with the card, given that this error is happening both on the phone and on my PC.

Could anyone think of any reason that this would be happening, or ways to fix it? Or should I just go get a different card?