Keeps overheating

I have a 2004 Dodge Durango that overheated a couple months ago but then hasn’t until a few days ago. It started off with the heat getting cold (I live in Montana and it’s 20 degrees) then the temperature gauge would shoot up into the red. Then it happened a few more times so I did a full flush of the coolant and replaced the thermostat. I also replaced the blower motor resistor since that was also broken. But now it continues to overheat even faster then it did before. I was thinking the next step would be a new water pump.

Well the heat will get cold if the water level is low due to water bypassing the heater core. It getting hotter faster to me would be that you now have air in the system after doing your flush. Get the air out of the system before you go replacing more parts.