"How was it determined what it was?" Behavior in the burrowing and then identified when placed between two strips of tape and viewed --ugly little monster, too! "And how did you ever think back on where you picked it up?" I went home when the itching got too intense so I wouldn't have to go to an ER not in my home town. I had been in dress shoes and a suit all day prior to checking into the HI in Gadsden, AL. The symptoms began quickly as the thingy burrowed along (it was in my back so I couldn't see the effects at first); the redness and swelling left a clear trail to follow for doctor's inspection from entry point.
I recently saw on Untold ER stories a gal that went to the Emergency because she had something crawling around under her scalp and she couldn't stand it any longer. She explained it would stick its head out but they could not get it. The Dr. looked at her head several times and could see nothing. To shorten the story, finally her husband ran for the Dr to show him there was hole on her head bubbling and it was coming to the surface. The Dr. hurried in and it disappeared. Ultimately, the little wormy thing did appear and it and another just like it were carefully pulled with tweezers as they surfaced from under her scalp.
If I recall it was some type of larva--can't remember, but it was another weird thing. She had been in Costa Rica and they believed she picked it up there in her hair and it burrowed in the scalp.
Going to bed and probably lay awake feeling all kinds of crawly things now. Have a good night.