Long term back problems, now sudden calf pain

I have long term back problems, and have had three spinal  surgeries in the past. I have been left with walking difficulties and severe pain, last night I started to feel pain in my left calf, about 3 or 4 inches below my knee. The pain gradually increased through the night, keeping me awake for most of it. It eased off this morning, but is now starting to build again. About three months ago a similar thing happened, though the pain wasn't so severe, and it went away after a few hours.
There is no redness or swelling, but my leg is really tender to the touch, and is also painful when I stand up or walk.
Is this anything to worry about please?

[garfieldsing]

Recently i have shooting pain from lower back down left leg and end at toes. Left Calf was in extreme pain after walking 2min. Calf pains goes off immediately after lying down on bed. The calf pain is trigger by walking movement.

How's did the pain started ?
Any calf pain when lying down ?
Can walk for how long before calf pain started ?