Well, if it lasted for a few more days as in it is still there, see a doctor. Most bug bites are nothing and go away. I wouldn't have worried but usually they also dissipate over time.
I just did a quick Google search, to be honest, without seeing a photo, it is difficult to tell you what kind of insect, but, from what I read, it could have been a type of spider. Again, it is important to see a doctor and as soon as you can.
Hello~You need to see a doctor, he/she will be able to look at it and determine what needs to be done. Keep close watch on it, you don't want it to get infected.