what is causing acne on my chin and what do I do to clear it up

It might be rosacea. You might try Metrogel https://www.mayoclinic.org/drugs-supplements/metronidazole-topical-route/description/drg-20064727

With all the Modern technology. I would go online type in some different things like roseola and other skin issues to see if any of them looks like what you got going on.
And if it’s been going on for more than two weeks, I would call your doctor and ask to be sent to a dermatologist
Are you using any new soap, shampoo, cream, rinse, anything that touches your
Even laundry soap and softeners if you
They all could have chemicals in it that your body don’t like And don’t forget make up
I had hives for nine months last year very painful. And it was caused by a vitamin that had a chemical in it. I had never had. It was grain alcohol.. But they put some fancy word instead of just saying green alcohol.
So do a little thinking what you have done different since this started or a new brand of something.
Wish you the best

In our 70s acne type eruptions are often rosacea. If you can’t get metro gel
then 2.5% benzoyl peroxide is OTC. I use Prosacea OTC on my rosacea.
Safe homeopathic gentle sulfur gel non-tinted.