Overheating Honda civic 2002ex?

it all of a sudden began overheating n spraying stream one morning. I replaced the overflow cap n coolant did no good. I replaced the thermostat and ran head gasket sealant through it and it did no good. We paid to have the water pump timing belt and alternator replacedand thermostat and valve cover gaskets and seals etc.it ran for about two weeks and began overheating again so bad n it would shut off while driving. We paid to have the head gasket replaced and head milled and it ran for about a week and it began slowly overheating and then shut down while driving. Another mechanic says the head gasket was done messy but Idk. When it first began overheating originally it would be in park and gradually go to red zone hot. I would turn the heat on n get NO heat inside the car or defrost.could the heater core b clogged and causing all this trouble? We have bought a new radiator too but haven't replaced it yet. What is causing this problem? We need our car to b FIXED!

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