Hack showing in search results

Ok two things are happening.

This shows up when I search the site on google.

GRO
girlsriders.org/
This site may be compromised.

Then on certain posts/searches this shows up.

BUY Isoniazid ONLINE NO PRESCRIPTION – Erin Wolfkiel
girlsriders.org/?page_id=2586
Erin Wolfkiel. by Courtney in. Skating 4 years Born in Chicago, Illinois Currently in Liberty Township, Ohio Sponsors GRO and SkateStandard Goals Use the …

It is always the same, “Buy Isoniazid Online no prescription” It shows up on search results for most but not all posts.

How do I fix these problems?

Thank you