Help! Betta has "bubble" on eye?!?!

[Rava]

I looked at my sister's betta today, and he suddenly (I mean, he didn't have it yesterday...) has this bubble looking thing over his eye. It looks terrible, but other than that he seems fine. What is this and what do I do?! Thank you for any help!:(

[SO00712]

Describe this buble is it like a whtish bubble that is right over the bettas eye covering the whole eye?

[Rava]

Yes, it's whitish and is right over/ covers the whole eye. It almost looks like his eye is swollen or something too...