Tailbone pain

Mon
Hi girls, 
Was wondering if anyone has had this experience or knows of it. 
Since about 3 days ago I have had extreme discomfort in my lower back, I have been able to walk and exercise (to some degree) but am not able to sit proper when sitting or even lying down. Now the pain is so sore I find it difficult to get up from my lounge chair and bed and can feel pain whilst walking. 
I haven't fallen or sat on anything hard so this is why I need some opinions. 
Thankyou! xx