It's last segment of Spine n can be damaged by Fall,Trauma, Sports injury, continuous sitting n post pregnancy. It can get subluxed or fractured due to trauma, n pain is same in both the cases ( little more in fractured cases). Don't damage it more by avoiding-2wheeler,cycle, no sitting without cushion, if not subsiding-treatment-Internal manipulation, with pain management.

Avoid long sitting. Avoid flat surface. X- ray must.it may be deficiency of vit d  so a check up of  vit d

Dear friend You need to visit a good orthopedic doctor for proper investigation.

You need to strengthen the muscles of your lower back and gluteal region so that it can prevent undue pressure

Postural Correction- Sit Tall, Walk Tall. Extension Exercises x 15 times x twice daily - lying on tummy, take left arm up for 3 seconds, then bring it down, right arm up for 3 seconds, bring down. Bring right leg up, hold for 3 seconds, bring it down. Then right leg up and hold for 3 seconds and bring it down. Repeat twice a day- 10 times. Bhujang Asana -- Lie flat on your stomach, keeping the palms out, bend the neck backward, take a deep breath and while holding it for 6 seconds, raise the chest up. Release breath and relax your body. Repeat the exercise 15 times twice daily.

Kindly consult an Orthopaedic surgeon to evaluate the coccyx region. An U- shaped cushion will help you while sitting. Gluteal muscle strengthening will help too.

Please consult Ortho surgeon and get a relevant x Ray done to check the coccyx bone. Local examination also required.