I just came back, and the mechanic showed where the coolant was leaking and warned about getting water in with the oil, the thing is, I've had that leak for a little while (I didn't think too much of it because it was so small) and driven through plenty of rain and puddles without any problem, but I did have the idle RPM bounce. He said it would cost a lot because it was DOHC as well (he said his brother got his head gasket replaced for a 4-cylinder truck and it cost 950 dollars).

How urgent is it for me to fix it, and is there something I can do temporarily so no larger problems occur until I get the money to actually fix it? He also said that the head may need to be machined as well.