Are these hives?

Olivia • SAHM 🤰🏽 10/17/2016 👦🏼 🤰🏽 8/31/2018 👶🏼 Carter and Leo ❤️

I’m so confused! He’s had prunes plenty of times and now today he got this rash after. I will say he did spread the prunes all over his head and arm it’s almost like he broke out only where it was touching his skin?