Avenue theme constantly infected with malware

I have a website that uses a wordpress theme called Avenue bought from themeforrest … it keeps getting repeatedly infected with malware .. is et up a sub domain with this address http://nicfitness.testedoutdoors.com/wp/ which is repeatedly showing as having malware in google chrome

This is getting annoying lol .. a friend of mine who is a developer told me to remove the timthumb.pho file and a few other js files and replace them with new versions .. when they were deleted the site appeared fine .. as soon as the new fresh versions were uploaded it was pretty much infected again within 10 minutes … im at a loss to solve this as im not a developer and im hoping someone can help???

thanks in advance