2003 Chevy Impala antifreeze leaking & fluctuating engi

I suspect that I either have a radiator leak or hose leak. Coolant has been leaking for the last few weeks. I can smell the antifreeze. The engine temp has also been fluctuating. I had the radiator flushed and new coolant put in and this helped for about 2 weeks but now it's leaking again. What could be the other possibilities?

Assuming that the radiator had to be replaced, what is the usual cost?

Degately