Welcome at HCM.
I have read details in your question.Your main complaints are pain at tail bone,feeling of weakness & excessive sleepiness.
It looks from your details that all this can be due to-
-Any heart disorder like decrease in capacity of heart or heart failure
-Coccydynia(cause of pain at tail bone)
You should do following to have relief-
-Avoid sitting on hard surfaces.
-Take a good analgesic
like advil or aleeve.
-Discuss fro your doctor about local steroid
Hope this will help you.
With best wishes.