I can't move my eyes at all, so I move my head/body instead. though despite them being still every time I move my head (except when reading) I have to take a second to focus on what I see, lots of movement gives me headaches and drains my energy very fast so yeah I get it.

however it has always been like that for me and since it's new for you, mentioning it to your eye doc wouldn't hurt

Has your vision gotten worse lately? I know I get tired quicker when my eyes have gotten worse, or my prescription is too old

I also sometimes get really tired in loud busy environments, so maybe it was just too much stimulation that day

Edited to add: did you eat enough that day? I always get like that if I haven't eaten enough.

I definitely have the experience that things are "moving too fast" for me to process them. Happens when my husband is driving, and I'll be looking out the window and when in stores. He'll often leave me behind because I've stopped to read/process something I'm looking at. My eyes don't hurt, and I don't get physically exhausted, just mentally exhausted.

I feel you. I have been getting super tired and unable to function at times because the blind “ring” around my central vision has been getting worse. Im almost to the point where looking around quickly will tire me out like you. Definitely think it has to do with our brains having to fill in gaps faster and the stimulus it has is less. Basically like trying to get a car to drive further on less gas.

I suppose it might depend on your condition. In the last year when I am really tired I seem to get temporary nystagmus (which I don't think is a thing but it's the best way to describe it) . My eyes bounce up and down rapidly, nothing stops it, not my will, not closing my eyes or rubbing my eyes etc.

We're you tired first and your eyes decided they were too tired or did the experience make you tired

You might want to try navigativing similar environments on your own at your own pace. Trying to keep up with a sighted person by doing things that they do is not going to have good results, you're sprinting in place while they're walking. There are different strategies you can use as a low vision person to navigate around and look for stuff, but they take time and space to develop. Maybe just have your mom drop you off some time and have her come back in 90 minutes, and just spent the time experiencing the place without a goal. Wander around and see how many stores and places you can identify without focusing in. You'll be surprised at what you can infer from a blur. Some brands have distinct outlines in their signs, and you can smell bath and body works or places that sell pretzels from pretty far away. Just take your time and build up some comfort with an unfamiliar environment.

What you're describing is very probably a stress response to what felt like a radically unfamiliar or hostile environment. I used to get those when I was taken to parties when I was pretty young, like 17, and it felt like an adverse environment. Your body dumps a lot of hormones and burns resources to keep up and survive in a difficult situation, and you have to pay all that back. If you can modulate your response by relaxing, that will mean you are less tired. This will likely only come with exposure and the development of skills that make you more confident.

I don't know what this could mean for your eyesight but what you are describing sounds a lot like autistic shutdown due to sensory overload. The florescent lighting in shopping centers reflecting from the displays and floors really screws with my ability to visually process my environment and can be physically painful. I have been visually impaired my whole life but only recently learned that I (42F) am also autistic. If your opthalmologist does not find an answer, the issue may not be your eyes.

We can't give medical advice on this sub, please consult a Dr if you have concerns regarding your eyesight.