Normal to shiver after a cold shower?

I was taking the cold showers for about a week. It was great.
I loved how I felt after the shower and I would have lots of energy all day.
The last one that week was different. I felt great when I got out of the shower like before.

Then after about a half an hour, I began to feel like I was shivering inside. It didn’t seem to be on the outside and it was very uncomfortable. The shivering lasted for hours that day.

A couple days later, I hurt my back and was unable to do the cold showers because I have to do a lot of moving in the cold water until I get used to it.

Today I felt like I was able to start up again. This time I could stay in the cold water longer because now I’m used to it.

The water was beginning to feel warm to me when I finished the shower. I’m not sure how much time I spend in the shower, but when the water does feel warm, I continue for a few minutes more.
Again I felt great for about 30 minutes. Then I started with the inside shivers again. When I get those it sort of makes me nauseous. It was around 78 degrees in the house. I hadn’t opened any windows yet.

I wrapped up in a warm blanket and after I finally got warm, I was okay.
Anyone else have any problems like that? Do any of you know what I might be doing wrong?

Maybe I’m not in as good of health as I thought I was. Should I continue or would that not be a good idea?

I haven’t tried the hot/cold showers yet. Maybe that would be better for me.
I want to keep doing to cold showers but I am afraid my body is trying to tell me something.
If you have any ideas, I’d love to hear them.