I Have A Red Itchy Rash In My Hair And

I have a red itchy rash in my hair and on my back across my shoulders, a couple spots on my leg, arm and on my chest area and stomach. red little individual bumps, not blistery. they are very itchy. first bumps showed up 3 days ago and I thought it was a spider bite, there were 3 spots on lower back and 3 spots on front breast. now I have them in hair, across back shoulder area and a couple on arm and legs and stomach. should I see a doctor?