Overheating?

Thge vehicle listed above is overheating. When bought 3 years ago the radiator, water pump, and thermostat were all replaced. No heating issues until this last weekend when the car overheated on the freeway after an hour of driving. When inspecting under the hood, coolant was all over the left side of the block. The next day, upon further inspection, no overheating was happening, all levels were good, water pump not loose. Drove it around for a few days with no issues. No troubleshoot and avoid future issues, did a coolant flush through a shop. No issues following that. The next day replaced the thermostat. The system was inconsistent in temperature. This morning drove it about 1.5 miles, and it overheated again but had no coolant sprayed under the hood. Replaced the thermostat again and the water pump with no resulting change. Our thoughts are there is a block somewhere or the heater core is shot. Thoughts?