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 $150.
Add at least 200$ if you have a service garage do it for you. That said, you can temporarily fix a leaky head gasket - IF the leak is a small one and you catch it early enough - with a liquid sealant like Rislone Block Seal: Head Gasket Fix (tm), it's about 30$ a bottle and lasts for 3 to 6 months or more (YMMV).