Rear End Problems

I have been having for some time problems with my rearend. It slides out from underneath me while driving down the road, it makes a metal grinding noise when i make a sharp turn, and it makes noise everytime i put it into gear. I jacked up the rearend, and had no problem with the driver side, but when the car went up the bottom of the passenger side tire fell inward and the tire has some play in it, i tried tightening up the lug nut just to be sure, and it didnt help. Are my rear wheel bearings bad? if so hopefully thats all thats wrong.

Thank You

Then car is driven hard (street raced) from time to time, i havent checked where the lower control arms attach near the body yet, will do tomorrow, but with the car jacked up, if i grab the bottom of the passenger side tire and shake it it moves, it wont come out that what makes me think that the bearings in the rear axles are bad.