Help Text sent from my phone that wasn't me! Help!

[Android Question]

I've had a bizarre call today from someone that I've apparently sent a text to whom I've never spoken to or met.
They sent me a screen shot of the message which was 2 emoticons of cats followed by "xx".
I remember the message they sent back which just read who's this which I didn't reply to because there was no history on the phone of me sending this message. I assumed they had a wrong number.
Whilst I appreciate that the picture they sent me could have been a fake, I checked with my network (EE) who confirmed the message was sent from my account at the time shown in the screenshot.
I definitely didn't send this as I've never sent an emoticon in my life and have no intention to do so. I was also just in the house at te time so no one could have had access to my phone.
What's made it even weirder is that no matter what I've tried I can't send these particular emoticons from my phone. It's only the one message sent about a month ago but it's still spun me out a little bit

Any help with this would be great as I am truly stumped.

 

[Hadron]

Orange (now EE) used to have a web gateway that let you send messages "from your account" without using the phone. If someone has cracked your account it would seem odd to advertise it that way, but if you use the EE website to access your account options it might be worth changing your password as a precaution.

You might want to check which apps on your phone have permission to send SMS, just on the off chance that it was one of your other apps sent it. Again, it's not obvious what the point would be (if you get a hacked app onto someone's phone why send ordinary messages to a random person??), but if you can identify all of the apps which have this permission, then any that are not messaging apps, or not apps you'd expect to be able to send messages (e.g. some security apps would legitimately have this ability), would be worth looking into further. Especially if any of those are installed from third-party websites rather than the Play Store. If you are unsure, just post the list of all apps which have the SEND_SMS permission here and we'll let you know if any of them look fishy (for example, I have 7 apps on my phone which have this permission, 3 messaging apps, a security app, an automation app, the Play Store and the Nokia navigation app - not sure why that last one has, but the rest all make sense and I doubt Nokia are malicious). There's an app called "Addons Detector" which can scan your apps and let you know which have which permissions.

 

[robbohkd]

It's just odd really. The only app with the permission to send messages is Whats app. Upon closer inspection it is the only place on my handset that features the emoticons in the message.
It must be something to do with that. There's just no logic!
The only other thing is that the message could some how of been routed incorrectly through my service provider.
Thanks for the response though Hadron. I really appreciate it.