Database Connection Error after new Theme Install

After I installed the Fashy-Lite theme by PremiumCoding, my site started getting constant “error establishing database connection” messages and still is. I switched from Responsive Theme by Cyberchimps because there’s only so much you can do to make it look decent.

– I get around 6,000 visitors a day to my site.
– I’m with Hostgator on a 4G VPS Server with 2 cores capable of handling 20,000 visitors a day.
– I have replaced the theme with the paid version and I’m still getting the error.
– All scans and test have been ran on server and everything is normal.
– Theme developer @ PremiumCoding double-checked their theme and said no one else has had this problem before me.
– Spoke with Sucuri, my firewall company, and they said I’m not under a DNS attack.

My question is, and this may sound dumb but I don’t give a shit, can a new theme use up a lot more of your resources on your server and could it be that I’m “maxing out” my current limits on my server because of the the new theme and the resources it requires to run it? How do I compare the two themes and how much resources each of them use up on your server?

The page I need help with: [log in to see the link]