Grapefruit Sized Bug Bite !?

okay, so i have this bug bite. it started out looking like a regular mosquito bite, then when i itched it it got very large. you can still kind of see the original bite area, but theres a larger slightly reddish area about the size of a grapefruit surrounding it, and it is swollen and slightly hard. this is the second time this has happened. the first time i got two of these bites on my forearm... they protrude so it looked like i had two lumps on my arm. what are these? am i allergic to some type of bite? i dont think i had any other symptoms... maybe a headache but not enough to really notice!

oh... i went to see a nurse and she thought it could be a scorpion bite or a spider bite?

it didnt have a scab or anything for a while and when it did it was from scratching it...