What causes a patch of extremely sensitive skin?

[sm664a]

Hello,

I’m a 24 year old female and I woke up this morning in quite a bit of pain because a small patch of skin above my left knee was being irritated by my blanket. When ANYTHING touches this patch of skin, it feels raw and burnt. There are absolutely no visible signs of irritation, trauma, or swelling.

Some possibly pertinent information:
I take 10mg Trintellix daily for anxiety and depression
I take birth control
I’m in the middle of a course of Bactrim for a UTI

I was in the ER two days ago for suspected kidney pain (I have a history of stones and it felt exactly like that) but they found nothing - all blood work and urinalysis was normal and an ultrasound was clear (I had started the Bactrim 2 days prior).

This sensitive patch of skin is extremely bothersome and I would love to know if it’s something I should be concerned about.