Loose steering

So iv been noticing in the past month that my steering has been getting much looser. Theres much more play in the steering wheel that usual. A few weeks ago I was having some rubbing sounds coming from my front right end, after it progressed I was told it was probally a ball joint. Well I did the test, jacked up the car and wiggled the wheel, Nothing, didn't move, so im stumped.
To add tho, how i can tell it's getting worse is that it dosn't like driving on the highway anymore, my wheel will constanly shake going about 60 and up. It's not a harsh shake, just moving about 1/2 a centiment back and forth when im driving, either braking or accelerating. I had the steering dampener replaced in August when I have my front brakes serviced due to 2 front warped rotors, that were also vibrating. So if anyone has any suggestions, please post them, highways are the only way to get places now a days