Any ideas what this rash is?

My little one started out with a few jumps on his right ankle. The pediatrician thought it was eczema after 3-4 weeks it was on both feet and his legs. Took him to children’s urgent care and was told heat rash (also he had thrush and is currently on meds for this). Now 2 weeks after that the rash is on both feet and legs still. It’s not on his hands or arms. I have a rash as well (only on my stomach no where else) but I’ve had it off and on since my csection 10ish weeks ago. No one else in the family even has a rash (we are a family of 6). His rash started around the time we started introducing formula, he was exclusively breastfed before that (side note I’m lactose intolerant so I don’t consume dairy). So out of curiosity any ideas what it might be?

Here’s when it first started

Here’s his foot now