Help with baby mourning dove

Hi! I recently found a very tiny baby dove on the sidewalk some days ago and I kept it in a box with some soft fluffy fabric. I need some advice to at least keep them alive while they grow.

What can I feed them? They seem to be in a very early stage of development. Unfortunately, I don't have access to their specific food, so I've been feeding them egg and cornmeal with warm water all mixed into a mush, and letting them drink it on their own. For clarification, I live in Argentina.

At what stage are they? They seem super young, they sometimes open their eyes and their length is about 6cm. I found them on the 5th of this month so I also wanna know maybe how many days old they are??

Should I get them any vaccine/medicine? I'm not sure if there are any vets that can treat them in my area but I'll search and ask a bit more, I just wanna make sure they need it because they'll be very expensive most probably.

I think that's all for now. I named them Topper. Here's a pic.

topper