Hello dear, This requires a clinical examination by an expert. Atleast need to know that does movement at your lower back influence the pain at your calves or not. Does the pain aggravates in lifting your legs up. Back problems like inter vertebral disc prolapse
) can not be rule out from an x-ray or blood tests. for this only clinical special tests and MRI of your spine are vital.Hence sincere advise to you is to visit a Physiotherapy
clinic near by you and get your examination done as earlier as possible. Wish you a good health soon.