I had a discectomy about three days ago, however the pain appears to be getting progressively worse, is this normal?

Not normally: Check to make sure you are not developing an infection by checking your temperature and seeing if the wound site is becoming red, swollen, tender, warm or starting to drain. Also there could be a possibility that your are herniating another disc fragment which occurs in 5% of disc surgery patients and can occur at any time postop as only the portion of the disc herniated is removed at the surgery.