Welcome to HCM,
You have not mentioned your age.
If you are elderly then possibility of having Osteo artheritic changes in your lumbo sacral spines giving nerve irritation
giving you this problem.
Go for x-ray lumbo-sacral region.
Consult spine specialist and go for the treatment, physiotherapy
as per advise given by him.
Mean while use hard bed for sleeping, do no bend and avoid weight lifting.
Ok and bye.