2013 Eco coolant/overheat problem

I have a 2013 Eco. I had been driving for about 30 minutes when I got the error message that I needed to idle my engine because it was overheating ... on a snowy day. I pulled over and popped the hood and the drives side of the engine compartment was soaked with coolant and my coolant level was almost empty.

I let it cool, filled it up and ran it in park for about 40 minutes without it happening again then drove back home. Does anyone have an idea what could be up? I was pretry sure the thermostat etc. Were on the other side of the engine.