Spotify connect unknown user???

[pajdegen]

Hi I discovered just now that someone else is using my spotify? When i tried to play some of my songs i suddenly got the connect tab choosing where I want to play my music from my device or from a stranger, 

How is that possible, even when I wasnt using wifi?

Now to the tricky part, of course I can always change the password, but the thing is that I lost 2 phones in a couple of months both of them samsung s5, now its a popular phone but, it says this strangers name is playing it on her samsuns s5, could it be that shes using my spotify account somehow?, from one of my lost phones, tried to use a fndmyphone app but unsure if I enabled it in that phone so he cant find anything...is there a way that I can find whoever is using the spotify and maybe connect them to my old phone? its a common name so i got alot of hits both on fb and searching her name?

Anyone has any suggestions?