Bruise is making me worried...

Blueswan • 🏳️‍🌈 (Pan/demi, she/they) A smart feminist who writes, sews, cooks, etc. kundalini/Sikh follower, and hopefully successful college student. ADHD/anxiety
I've had this for days, and I don't know how I got it. This has happened before, but they didn't look this bad. How do I get rid of this bruise?