I woke up from radiating back knee calf pain to the ankle. itwas relieved after taking diclofenac. what could be thepossible diagnosis?

See details: Your description is not specific enough but possible causes including knee issues teat, strain, tendinitis, etc) or muscle strains or pulls. If it persists, have it evaluated.

Sciatica?: Pinching a nerve in your low back can cause pain to radiate from your knee to your ankle or foot. It could also be a problem in the knee joint itself, or even in the calf muscle. If it recurs, you should be evaluated by a doctor.

Nerve?: It may be due to a nerve entrapment from your lower back. Mri will help determine the cause but can be due from many other things.