Trying to fix hack/spam?

My website: http://www.thedrc.net

Couple days ago I noticed we had an extra admin. After reading on here, I messed with ID numbers until I found him, made him a subscriber and deleted him. All the categories were set back to default for some reason and in almost all the post I found links like this:

<em style=”display:none”>Betrayed rip <div style=”display:none”>Overnight Delivery move</div> <u style=”display:none”>A Life Less Ordinary film</u>

Anyways, I went through and deleted all of them, redid the categories and went in today to discover new links and most everything screwed up again. Does anyone know how to fix this? We are upgraded to 2.8.6 now. Is there anywhere I can a step by step explanation on how to fix this? Does anyone have any suggestions?

Thanks for any help or suggestions!