Clicking And Scrolling Issues

I've had my mouse for a few years, but the last few months or so I've had problems on and off with it. I was just putting up with it before, but recently they've become so bad it's difficult to use the mouse at all. The most problematic issue is that the left button (and sometimes the right one) will mistake a single click for two or more clicks. This only happens sometimes, so I don't think it has anything to do with my computer settings (which are the same they've always been anyway), but it's become increasingly frequent. This makes even simple navigation in my computer folders difficult, let alone anything more complicated. Also, even if I'm holding the button down securely, it's like the computer thinks I'm clicking it on and off rapidly. The other issue is that when I use the scroll button, sometimes the computer doesn't react. If I scroll it a lot, it will scroll some, but it won't read every turn. This issue has also gotten worse. It barely works at all. Sometimes it even goes backwards. I would appreciate any help I could get.