Wireless keyboard connects and then goes wild

Hi there, I have a wireless / bluetooth Apple keyboard that has worked ok for years with no issue. Until recently, wherein it connects ok via bluetooth, then goes wild - starts typing itself, putting computer into mute and out of mute constantly. Then keyboard doesn't work at all. Shows as still connected, but won't let me type, and when I do try and type what comes up on screen does not match the characters I have typed in. So I have to disconnect it.