2002 sonata transmission woes

I have a 2002 sonata gls (automatic with shifttronic) with a little over 60,000 miles. At the end of making a 2,200 mile trip, I was on the highway and the car would not shift into fourth gear. I tried manual using the shift tronic but that did not prove results. I immediantly got off the highway and pulled over. I then proceeded to check the transmission oil as described in the manaul. There were no problems with the fluid. I turned on the car and made a test drive in which I found no problems. Concluding that there were no problems I drove the rest of the trip but then started to have power steering issues. I stopped at a local gas station and checked the power steering fluids and found that it was empty. Purchasing fluid at the gas station and filling the power steering resivour fixed this problem. About 15 miles away from my destination I started having transmission problems again, I was not able to switch from second gear to third now. I pulled over, turned the car off and then back on but still had problems with the car switching gears. Now I do not drive the sonata at all and it has problems switching gears constantly. The only clue I can go on is that I hear a whining noise being made by the car. Thanks in advanced for all the help.

Edit: I have had no previous problems with the car.

Does the car only have a problem with fourth gear? And does the fault occur when using the Shift-Tronic or full auto or both? Also, have you had the 60k mile service done on this car yet (including timing belt, etc etc)? If nothing else, go ahead and change your transmission fluid. Even if it doesn't solve or help with your problem, it definitely wont hurt.