You are almost there. Keep the pool at shock level today and run the overnight test again tonight. Vacuum and back wash as needed. Keep the pump running 24/7 until you are through shocking. If you pass the overnight test and the water still looks a little murky, turn off the pump for a few hours and let everything settle. If it looks clear after it has sat for a while, then you will need to back wash well, vacuum very slowly as not to stir up too much of the sediment and keep the pump on 24/7 until the water clears. When you have passed the overnight test let the FC drop to normal levels (which should be 8ppm for your CYA) and keep it there. Run the FC test daily until you get a feel for how much chlorine you need to add each day. Then test weekly.