Facebook mobile sign-in issues,halp!

I’m not sure if this is the sort of question that mods frown upon, but I’m stumped and know that fluthers are the wisest of all species.
For the past few days my facebook mobile acct has me signed in as some random stranger and won’t let me logout. Anyone else encountered this? How do I stop myself from changing their status updates to inappropriate things about their mamas? It’s so tempting!!