What Causes Rashes With Severe Itching On Palms And Front Of Hands?

I have the flu for about 5 days and still have a fever, in the last day my palms, front of my hands by the fingers and soft area of the inner arm is breaking out into a rash that itches to the extent of pain. I have a topical cream for itching but it s not controlling it and seems to be spreading. I was also on an antibiotic for a tooth extraction. What can be causing the itching and how can I control it so I don t want to tear my skin off. Thanks