A tick

Edit for whole story:
Didn't even notice the bite, but about 2 weeks after a hiking trip, I noticed a red rash on the side of my lower leg.
I waited for it to go away on its own but it didn't.
It grew into a 10 inch by 5 inch bright red patch that itched, felt like rice paper and hurt to the touch.
The edge around it turned a different color every day.

So one morning, my girlfriend at the time had enough and basically forced me to seek medical help.
Problem was, it was a Sunday, and the doctors in my area were currently on strike.
So I rode the bus to the hospital, and had a bit of a surreal experience there.
(I was running a high fever by now, so my recollection is to be taken with a grain of salt)

I distinctly remember walking into the emergency room of the hospital through the entrance for ambulances, cause all other doors were closed.
At some point I was standing in a back room of sorts, no other patients around, and 3 doctors who were on strike curiously looked at my leg.

They assessed that it's definitely a burn wound. I vehemently disagreed.
So one of them wrote a prescription for a wide-band antibiotic, based on guessing.

I went to the nearest emergency pharmacy, collected the meds, took them and 3 days later the rash was gone and the skin began to heal.