My USB Flash Drive keeps on needing formatting?

So, I plugged my USB stick into my computer yesterday and it said it needed formatting. I did, and I used it like I would have normally again, slowly adding all of my things back on to it, and then ejecting it safely.
I went to plug it into the computer again today, and it says it needs formatting again. I don't know what is wrong with it, or whether there is a problem with my computer, as I don't want the same thing to happen to my other USB.

Thanks to anyone who can help.