Thanks for the considerate report, Kathy.
We haven’t had other users reporting this, but I’d recommend adding HTTPS to your site, especially wherever there’s a login form, such as /wp-login.php or if you have a page like /membership/sign-in/ or /membership/register/
If you don’t add HTTPS yourself, you might want to use Jetpack’s Single Sign-On functionality, where you actually use WordPress.com to login to your WordPress.org-based site.
Jetpack actually has many more security features, too: https://jetpack.com/features/security/
Whenever your site gets compromised, you’ll want to consult some resources, such as the following:
Also consult your web host about the issue. If it keeps happening, I suggest switching hosts.
I hope it goes well.