Transmission or Torque Converter not working properly

Thank you for your response.
I'm still working on this issue.
I'm going to try to fill you in on all of the details of what I have.

Friday evening on the way down to Columbia from Charlotte Car in D5, first had issue on highway when turned on cruise control, going around 70MPH, RPMs revved up 6,000. Turned off cruise control, drove it around 70MPH steady for another fifty miles, made it here to Columbia, I travel back and forth each week. Next day I checked for any leaking engine bay and under car, did see power steering fluid on top of reservoir, and realized that the top wasn't tightened right, but just flushed power steering fluid last week. (Total different issue) Drive car up and down the road several times, whining noise coming from serpentine belt, even though it's new, added a little conditioner and it was quiet again. Hear grinding sound when turning steering wheel back and forth, still somewhat tight/hard pull. Drove around ten miles around the block, turned at light was probably ar1/2-mile, car basically felt as if in neutral, no acceleration in any gear, just coasted downhill pulled off side of the road. Turned car off, checked/looked to see if anything is noticeably different, car would crank up, can move shifter, after 20 minutes. Put into G5 and was able to accelerate forward and backward for about 3 minutes. Then it lost acceleration again, all lights are on, engine light has been on but only getting a P4636
(or P3646, I can't remember exactly) but that's the oil pressure circuit arm switch. No blinking light on dash Gear module. Approximately 190,000 miles, only had for a year and I've kept up with regular maintenance, and I've put close to 80,000 miles since I bought it, is time for oil change, was going to do that over the weekend, but this happened. It will still crank and sometimes it will move when put in gear, but only for a few minutes, transmission fluid is dark, doesn't smell burnt from what I can tell.
Unfortunately, I can't speak for the vehicle past owner maintenance.I saw that the transmission fluid was changed back in 2017 in the car log. But that's all I know.
Any suggestions on what to do, I'm out of town, away from the mechanic I use regularly and stuck in a bad situation, and horrible timing! Any help or advice is greatly appreciated.
Thank you,
Jen Heavner