spider bite??

i’m 29 weeks pregnant & i have this hard bump on my butt , it hurts when being touched and it has gotten bigger since i’ve first notice it 2 maybe 3 weeks ago..& the last time i shaved was around the same time i noticed it,but the bump wasn’t there yet. it looks as if it’s spreading .. could this be a spider bite ? Sorry about the hair , i’ve avoided shaving just incase.