1996 Mazda 626 leaking coolant

Engine Cooling problem
1996 Mazda 626 4 cyl Front Wheel Drive Automatic

my car is leaking coolant from beneath the engine cant see where the leak is exactly, but dripping near the oil filter, flushed and sealed the radiator 2 days prior had massive overheating, smoke coming through the airconditioning grill, any ideas on the leak car starts and idles ok starts heating on small trips im no mechanic with minimal funds am hoping its just a thermostat problem help