Like the OP I was hit from behind while sitting still and the other car was doing about 40. I was leaning forward at the time of impact because I had just completed an emergency stop and the Jeep I was driving hadn't settled yet.

I didn't notice anything out of the ordinary at first. I didn't realize that I had lost consciousness for a few seconds until later. I had a bloody nose even though I know I didn't hit the steering wheel. The pendulum effect of the timing of everything threw me back into the seat hard enough to break the seat.

It was a couple of days later that I was driving from church to the local WalMart. This is a trip I'm very familiar with since I've done it at least once a week for several years. I remember blinking and everything was gone. I had absolutely no memory. The lady in the seat next to me was a complete stranger and it took another 15 minutes for me to realize there were kids in the back. It turned out that she was my wife and those were our kids.

I lost the ability to speak clearly for a while and had a horrible stutter for a couple of months. I got treatment early and I've made it a long way back but I'm not sure I'll ever be 100% again.

The reason for this post, however, is that I have been getting both hot and cold flashes. It would be 100 degrees and I will get cold randomly. It is usually associated with getting a drink but it can take thirty minutes for me to warm up again. I will also randomly get extremely hot. I can be sitting in an air conditioned room with fans blowing directly on me and it feels like the fans are blowing hot air. I start to sweat profusely to the point of soaking a dry shirt in just a couple of minutes.

Because of the pills I take as part of my treatment I have to drink a regular amount of water each day so I know I'm not getting dehydrated. Yes, I am a bigger person but I've never had this issue before.

Speaking of being bigger, I have started gaining weight at an accelerated pace despite a drastically reduced diet and increased activity.

I'm also not sleeping very well (possible apnea) and despite getting several hours of extra sleep on some days I still feel exhausted all the time.

Thought someone would find this useful.