this thing on my arm started out as just looking like a small bit of dirt on my arm after being in the woods behind my house. it grew and turned into a scab over the next 24 hours. i did not scratch it or injure myself. the area around it was really itchy but i've been putting itch cream on it. it was like that for a few days. yesterday the scab fell off and it looks like this

i've google searched the fuck out of it and nothing quite fits. going to the doctor isn't really an option for me at this moment since my mom is in the hospital and my dad will just not care. any advice? anyone know what this could be?