My left hamstring and calf cramp, is this related to a disc herniation?

Sciatica : Sciatica is a definite possibility. This usually is caused by pressure on the nerve commonly as it exits your lower spine from a disc bulge or herniation, or possibly from a bone spur. Stretching exercises, physical therapy, chiropractic care are all reasonable initial treatments. However, if the pain persists or is associated with more severe symptoms such as numbness, tingling, weakness, or bowel/bladder incontinence -- you need to seek medical attention from an orthopedic surgeon or neurosurgeon.

Could be: See your doctor for help in evaluating this. You may need an MRI of your lumbar spine for definitive diagnosis if your meet criteria for this study.