I don't know when I'm next seeing my psychologist ( shes going on annual leave )  and I've kept putting it off about talking to her about this.
I know what trichotillomania is, it's when people pull out their hair, one by one.
I don't pull out my hair, but I skin-pick. For ages, since I was pretty young I sorta scratched my head, and dandruff flakes would come off, and I'd put these on a pile. Did this a lot. Anyway, I didn't really think about it but the feel to want to do is getting more? Like something I automatically want to do. Anyhow, my ears and shoulders got sunburnt over summer and when the skin went peely, it felt really good to peel it off. Super satisfying, and something I'd want to do. My ears got burnt so I pulled the flakes off them too, but now they have three spots, two on one ear and one on the other where a scab forms, pretty small, but every day or second day I can pick this off.

I want to stop doing this because I do not think it is very healthy, plus the scab on one of my ears is getting kinda weird. I haven't done this for two days ( I make it to Sunday I buy myself something from the grocery store ) but I would like to know, what it is, why I want to do this, what do I do to stop?
All day I would find myself fingering my ears and wanting to pick the scabs and flakes of skin.

The name you are looking for is Obsessive compulsive disorder and it tends to be common for people under some form of stress. It's not easy to deal with because it becomes a habit that's hard to break but it can be controlled. In addition, there are medications available that can help as well. If you search for it on the internet you will get many hits because it is somewhat common. You therapist will be able to help with this so ask about it as soon as possible.

That's dermatillomania, or just skin-picking. It's not Obsessive Compulsive Disorder, but it does have some overlap. (I have trichotillomania and some picking issues, but I don't want to elaborate much lest that trip other people's trich/picking.)

Definitely tell your therapist when you can. Until then, it might help to give yourself something else to pick at. I've heard a lot of people recommend letting drops of regular Elmer's glue dry on your arms or wherever else you like and picking them off instead of targeting scabs or dry skin. It can give a similar feeling of relief without the damage.

Normally I'd recommend putting a bandaid over scabs so they're not as easy for you to remove before catching yourself, but that's not very practical for your ears. Putting some lotion on your ears might help, or wearing a hat could slow down the scalp scratching. The hardest part for me is noticing what I'm doing before I've already picked or pulled, so anything that makes the action harder might help.

For me, a spike in trich/picking indicates I'm under a lot more stress than usual. I know saying to reduce stress isn't terribly helpful advice, but if there's something else stressing you out that you can work on, addressing another issue might help the picking too.

There are a lot of resources for dermatillomania out there. A lot of the general advice overlaps with trich, so consider giving that a look too.

Thanks for the answer. I'm not sure when my therapist is back but I've got an appointment with the school nurse so I can talk to her about what to do for now.