I have had sharp pain near my tailbone for nearly a week now. There is no swelling or pus. It hurts little bit when I try to sit back. What shud I do?

Coccydynia. A painful coccyx can occur without trauma. Try anti inflammatory, avoid sitting directly on the coccyx by using a donut pillow, and decrease your acitivity. If it doesnt improve, have it checked out.
If you fell down.... ..You may have cracked your tailbone, which is easy to do. No real treatment other than tincture of time. If there is no history of injury to the area, you could have an infection - the most common is called a pilonidal sinus - which often requires antibiotic treatment, and sometimes a minor surgical procedure. If the pain persists, see your doctor or a dermatologist.