Very loud continuous metal grinding noise

I have a 200 monte carlo. My husband just replaced the drivers side cv axle because it was knocking when turning. Everything was going good for about 3 weeks then the knocking sound was happening again. We thought it was the passenger side now since we already replaced the drivers side. Just the other day my husband was pulling out of a parking spot and all we hear is an extremely loud bang followed by a continuous grinding sound coming from the driver side (sounded like from the cv axle area) we automatically shut the car off got out to see if it snapped and couldn't see anything. My husband went to turn the car on and the second it was started there is an extremely loud grinding sound. Sounds like metal on metal grinding coming from the cv axle tranny location. We shut the car off andcalled a tow truck to make sure we ddidn't damage anything more. Once home my husband put it on a jack and there is play with the cv axle, but my husband and father are mechanics and never heard that sound when a cv axle goes. Now we think the cv axle we put in was defective but afraid to replace it and find out the noise is still there. The car will start, will go into neutral (still very loud) wheel does turn (we pushed it out of traffic since we were in the middle of the parking lot drive way). Please help! If you think it is the cv axle or something worse I need help!