Overheating

I have a 1987 Pont. Trans Am gta it has a 5.7tpi motor with 165000 miles. My problem is the car is overheating and when I try to add coolant the fluid is shooting out of the radiator. I know it sounds like a blown headgasket but could it be something else.I don't see or smell any coolant coming from my exhaust also I never noticed that it was loosing fluid internally just what came out of the overflow.