My 97 blazer 4x4 automatic will not shift past 2nd gear. When I manually put it in third it feels like it is in neutral. I just brought it in for an oil change last week and they had to add 4 quarts of tranny fluid to it. The fluid in there they said was almost black. I am a single mom and cannot afford to spend too much on a transmission rebuild or even getting a new vehicle. What could this problem be?