Rash on baby?

This showed up on my babys leg yesterday and i thought it was just dry skin but we woke up and it was worse. No fever, just rash. My mom is saying we should take him to the er but i think we should just wait until his dr app tmr? Opinions? Im not tryna to go to the er during a pandemic. Also i did wash him in johnsons wash and thats the first time i have but i dont think thats it. We rebathed him in his usual stuff today