Why are someone else's photos appearing in my photostream?

Nope, not sharing with anyone else (although where and how do I check this to be 100% sure?)

I will change my password now as a formaility...

This is really strange.

Yeah- they're on my camera roll and my photo stream.

The only time someone could have taken my phone is at work or at home and these pictures are in a hotel room, on a bus and a landscape shot of another country, there's no way these could have appeared from someone taking the phone.

So that narrows it down to someone taking pictures using my Apple ID, but presumably I can't trace that, can I?

I'm going to upload the photo's on to iPhoto when I get home, see if they're time/date stamped and can offer an insight...

But that's the thing - I haven't. 1 of the 7 pics looks like it's been saved from the internet, the other 6 are pretty much of the same 2 people as if they were on a night out. I don't recognise them or where they're being taken.

Also, going back to the last photo which I did take (which was yesterday afternoon) these photo's have appeared in the last 12 hours, and I only really noticed them after EE reset my network settings and asked my to turn my phone off/on.

Do you think that could have something to do with it?

PROBLEM SOLVED.

It would appear that WhatsApp is to blame. Photo's posted from within a group conversation were automatically being added to my camera roll and photo stream. Was also happening to my friend.

Hope that helps someone!