google forms – Regex to not include letters and values without spaces after commas

I have a text box and I need to validate the date that is being input. I’d like the users to only input numbers and if they input multiple numbers separated by a comma I need them to always add a space after the comma. I want to only accept data that looks like this: 1234, 15482, 086392 or 16843
I don’t want to accept data if it looks anything like this: 13738,74848, abc , 6a738

I’m using a google form here so I need a Regex that matches the above criteria.

I have two Regex ,[^ ] and [A-Za-z] but I can’t figure out how to connect them.