People trust many websites today including ticketing sites, real estate sites etc. The issue is most malware and trojans are being injected into sites we actually trust. This can include YOUR website.
If you want to be as sure as you can if your website is clean, go to Securi Sitecheck, type your URL and check for any malicious code or blacklists you may be on.
You will see results like below (Sterling IT is safe!). if you find your domain has any issues or is on a blacklist, contact Sterling IT as soon as possible. The longer you leave it, the longer it will take to reverse.