You call NERD as mechanic, when he did the work why the head was left lose. a tool called Torque wrench is needed to perform the job to specs & seasoned mechanics with some tech knowledge always change head bolts when it is removed from the engine upon over heat. Kick that nerd between legs twice
you need rework as follows:
a. replace head gaskit, replace head bolts, check water body & coolant intake pipe for rusting replace if corroded.
b. clean the radiator, change hose pipes, check the radiator cap replace if duff
c. replace thermostat in cooling system, make sure electric cooling fans are rigged to work automatic
d. prepare coolant in bottled water
e. top up reservoir tank with coolant to HIGH mark only
get car rolling