When I'm driving, at times my steering wheel gets stiff and my brakes seem to lock up. I thought I needed power steering fluid so I was able to get to a close gas station. After finally finding the power steering fluid tank I purchased and tried to add some fluid and it was basically full already. I just fill it up a tiny bit. I tested turning while in park, drive and reverse and it did well for about a week and then it happened again. I repeated the same as above and again it was full. It just happened again the other day and it was full. I added a tiny amount. I seem to feel like it's something else but not quite sure and how much is this going to cost. I've had this car a little over a year and I've put more money on repairs than I've had to on any car I've had. This is my first Nissan and may just be my last. Please provide suggestion. Thanks.