Children's Book Authors/Illustrators discussion

I am seeking advice on getting a manager or agent of some kind. I self-published my first book and want to get started working on my next one. Unfortunately, keeping up with my first book's marketing/media/sales/emails is taking up all my time! I am wanting to remain self-published, but would like to be able to work with someone who can help me manage the marketing/PR, emails, sales and overall campaigning. I am looking for someone who would take a percentage of the book profits, like an agent (instead of getting paid by the hour). Are there people like this that exist or am I wishful thinking? If there is, what would their title be, and where would I find them? THANK YOU!