I Have A 6 Yr Old Who Finished Taking Amoxicillin

I have a 6 yr old who finished taking amoxicillin after 7 days. The day after he got red blotchy bumps that itch all over his feet. The following day the red bumps have spread to everyway even his face,palms and soles. He also has a cold but no fever. His doctor said that it's a viral rash and not an allergic reaction to the amoxicillin. What is your thought?