Saturn Transmission

I purchased a 2001 Saturn SC1 that now has 73,000+ miles on it, and I had brought it to a local mechanic to change the oil and have him overlook the entire car for problems, as it is a used vehicle. He stated that Saturns are notorious for transmission leaks. The problem that i'm having is that ever since then I thought the car just seemed different, then while driving it began to "jerk" into second gear. I thought it would be fine for a while, but when I parked the car and then put it into reverse the car lurches very hard. We checked the transmission fluid and it was bubbling. I am not sure what this means, but I am not going to drive it unless driving to the mechanic.