I don't know what's causing my swollen upper eyelid?
If the swelling does not resolve in one - two weeks see an ophthalmologist so that he or she can evaluate your upper eyelid.
Unfortunately this forum is best for discussing more general aspects of cosmetic concerns.
It is not a substitute for getting care for acute issues. I strongly recommend that you see your general ophthalmologist to determine if there is some immediate issue that needs care.
Concerns about your lid
require that you see a local eye doctor for an evaluation and review of your history. Swelling is nothing urgent and it could simply resolve on its own. But if you're concerned, you should invest in seeing a doctor about it.