1996 Toyota Tercel Blown head gasket?

A few nights ago my dad looked at my engine and we saw that there was green coolant on top of it. It was mainly on the right side and a lot of it was on the battery. We then proceeded to check the radiator and found that there was no coolant inside of it. The next day we put more coolant in it and the morning after the radiator cap was empty yet again. We put some more coolant in it yesterday and this morning the overflow tank was full, the radiator cap was empty, and the oil looks as if though it has a milky substance to it. I took my car to this guy who works on cars on the side and he put some of that radiator stuff in it that will patch small holes to see if that could of been causing the coolant to leak. It obviously didn't work being that there was no coolant in the radiator this morning. What could be the cause of this? We can't find any leaks from any hoses and there are no puddles under my car whenever it's parked for long amounts of time. I live in Arizona and am supposed to be driving to California in 10 days but if my engine is messed up badly then that can't happen.