Have a boil on butt, very painful, about the size of a quarter now, & hot to the touch! How can I get some relief?

Needs attention. A large boil like this needs to be opened. I would recommend being seen by your physician or urgent care (not recommended you do this at home). An incision and drainage is the likely procedure pending full exam and history taking. You may need to have the wound flushed and packed, depending on size and depth as well as a possible antibiotic course.
It needs drained. What your describing is likely an abscess or localized infection. These are best drained and or surgically removed in order to limit the chance of recurrence. In some cases, warm compresses can help small abscesses to drain to the skin surface. If it is not resolving, you should seek an evaluation from a medical professional.
Drainage. Boils (abscesses, carbuncles) are skin infections that have formed pockets of pus and infection.They need to be drained in order to heal, otherwise they will get worse and can cause serious problems.Based on the size and location, you should see your doc to have it properly opened and drained rather than attempting to deal with it yourself. Drainage may be as simple as an 18g needle.
Hot pack & see a Dr. A boil can get very painful, especially if you have to sit on it! for immediate relief, take max dose of a pain-reliever of your choice (tylenol, Ibuprofen or aspirin), and apply a washcloth soaked in hot water for as long as you can stand it. See a doc asap (urgent care usually open on weekends) to have the infection properly drained -- trying to lance it yourself can spread infection deeper.