Hi Danni, most probably all your problems have cervical origin. Since you have a schedule of long hours on computer, it may lead to tension in nerves arising from neck while at the same time there is a possibility of carpal tunnel syndrome alongside( this will give you numbness and tingling in middle finger, atleast initially when it started). Also like you have mentioned low backache and leg pain pointing to tight fascia and probable accompnying lumbar discogenic problem. the picture can only be clear with careful examination or x-ray/ct scan for a clearer view.
In the mean time check your posture while working. keep your back supported, take small breaks and do simple stretches in it. Follow a proper flexibility regime routinely.