For short periods of time, prescription medications (such as narcotic pain medications or muscle relaxants) may be helpful to alleviate pain or related complications.
It can take anywhere from 4-10 hrs. now if your head gasket is warped you will have to take it to have it milled that takes from 1 day to several days. if not you can just buy a completely new one that fits perfectly for about $150.
Why would a bad head gasket cause the coolant reservoir to fill up? I noticed my car was overheated today, so I pulled over. It only took maybe a minute (with the car off, hood open, and fan on) for the temperature gauge to start falling, so I figured that I probably hadn't done any major damage.