“腿跟到膝盖窝很难受,..像是麻…”

You are likely to have Sciatica because  the sciatic nerve is entrapped due to the muscles imbalance, the joint misalignment, and the compression of the lower lumbar spine contributed by  prolonged sitting at the desk all day.

In your case, active exercise and postural training would be very helpful, effective and safe to eliminate the dysfunction if you could find a qualified personal trainer.