Power Steering is weird

I have a 1992 Toyota Camry. It always runs smooth, never really had a problem with it only a few minor things. Yesterday I was driving to work, I turned onto a street and something sounded like if I had picked up mud on my tires, exactly like it, so I didnt make too much a big deal out of it until the next time a had to turn. The steering was awful, it was so hard like the times your car just turns off and you're trying to get to the side of the road, that kind of hard. I checked under the hood and uhder the car and everything seemed fine. My power steering fluid was a bit low but I dont think it was enough for it to do what it did, it was in between the "max" and "min" line. Its fine on curves and when I dont have to slow down too much (smooth as ever), but when I turn at a stop sign or traffic light, its pretty hard. What could this be? Someone please respond to me. I dont know too much about cars so I hope someone can advise me.