2007 Nissan Sentra Engine/Transmission Issues?

For the past couple of weeks I have noticed a pinging from my engine compartment. Did some research and found that a possible problem could be the fuel octane I use. So I upped the octane of fuel I use to see if that would help. Well 3 full tanks later the problem has gotten worse. I have also noticed a loud whine when I accelerate and today lost partial power from the engine. Driving on the highway the sentra started to rev RPM's from 3k to 4k automatically (no change in gas pedal location) at a speed of approximately 70 mph. After about 5 miles of that, sentra then decelerated to 65 mph but was pushing 4k+ RPMs. Once I excited highway and started the turn off to the crossroad, the vehicle had no acceleration or normal power (cruising at most 10 mph). Even if i floored the gas pedal, RPM's stayed below 2k and never exceeded 10 mph. There are no warning lights illuminated on the dash board, with the exception of the tire pressure light. It is a 2007 with approximately 80k miles. Can anyone help with this issue????????