Suggest Treatment For Severe Itching On The Scalp And Neck

I had a late dinner (raw fish - sashimi) and came home. Never had a issue ever with raw fish, but I also haven t eaten it in some time. Within an hour or so I was itching on my scalp and neck first and inner arms. Didn t think anything of it until I couldn t sleep after about 4-5 hours. When I got up I saw a minimally raised rash on my inner forearms, upper arms, back of my neck. I took two Benadyl and then a Zyrtec in the morning. By late afternoon early evening it was really bothering me and I took two more Benadyl. When I got ready for bed I noticed the rash is now all over my back, stomach, chest, sides and the sides of my hits as well as my inner forearm/upper arms and back of my neck. There s nothing on my legs or groin area. I feel itchy, but also this weird wave of tingles as if I just got bit by a spider. Or at least when I immediately was bit by a spider in the past. Is there anything I can do to figure out what this is before needing to go to the doctor/hospital? Or any other better over the counter meds I could try that would help first? Thank you.