Should I get this bite taken a look at by the Dr?

So about 2 days ago, the top of my ass started to itch real bad and when I stared scratching it, I felt a tiny bump and I thought oh I must have got bit by something. The next day it turned into a big bump! It started hurting and stinging real bad and it was really red. Now today, I still can’t sit down on it too long because it hurts real bad. Now it looks like it’s blue and red like a bruise almost. It looks flat in the picture but the redness is the whole bump, the bump feels like it got bigger and wider. I tried ice pack but it didn’t work. Someone said spider bite which it could be, I do get allergic reactions to bug bites but usually by now they go away and this is only getting bigger and hurting more.

This was yesterday

Now it looks like this:

I do want to point out that the redness is not from me scratching it, I stopped so it wouldn’t irritate it anymore but it’s still red and the red lines around it is just from my underwear.