if YOU were really sick, please attach Doctor's certificate certifying NOT fit for travel. This will be taken into account by the authorities when calculating refund.
Always in TDR tell the truth about the reason for NOt boarding train.
I had a case where the person could not board the train. He was held up because of a landfall and the road was blocked some 25 kms away. I got the refund within three days of filing the TDR.
Hence...
more... if it is true, then you will get proper refund in a quicker process.
One TDR I filed with just Did not travel as the cause....the refund is yet to be processed although it was in end August.
Good wishes.