Suggest Medication To Reduce Excruciating Pain Under The Knee Cap

For a month now, I've had excruciating pain under my left knee cap. I can bend my knee sometimes, but it hurts badly when i stretch my leg straight again. I can walk but I limp, keeping my left leg straight at all times. I've been wearing a brace (which makes any slight bend in my knee hurt), icing 2x a day and taking 2-3 800 Ibuprofen's a day. Got a cortisone shot two weeks ago and it did absolutely nothing. Doc gave me work restrictions so I can avoid walking too much at work and taking stairs. It's not getting better. Not sure what else to do?