Fired for wrongly accused for stealing money?

So my manager fired me because they thought that I had stolen 50 plus dollars from the cash register where I worked. But I'm innocent and have NEVER stolen money or anything from work. The only possible reasons to fire me for that is if they actually had solid proof that I did it, which I didn't, or someone had accidently made mistakes on register which also wasn't me because I don't make that many mistakes it that it would add up to 50 plus dollars. They said it happened only when I worked but there are 3 total registers and we don't always use the same one every time. A theory I have is that it was some kind of downsizing thing because they're having financial problems and can't afford all of the employees they have. Idk what to do. Any ideas??