Yesterday I was alerted to a problem on one of my web pages. One of the photos I used (of storm damage) was instead a "girlie" pic! And just now, a different photo on a different page was instead showing some cocktail glasses. This appeared only on 3 different Verizon 3g and 4g phones. No other device showed the rogue photos. And the rogue photos disappeared later.
So it seems like the phone's browser is loading substitute images. How can that be?
It's likely that your website has been hacked.
If you use a CMS and haven't been keeping it or its plugins up-to-date, that's usually a common avenue of attack. Newer versions usually patch old vulnerabilities.
It's usually best to restore the site using a backup from before when the symptoms appeared. Then update your CMS and plugins and change all your passwords.
We don't use a CMS. We can certainly change the password though. Thanks for the suggestion.
I'd also advise you to double-check your site and make sure that there are no files there that shouldn't be. Likewise, check all the existing files to see if they've been modified (or delete everything and upload clean copies from your computer).
Make sure you aren't hotlinking somebody elses image