Look Up Data From Multiple Columns And Insert In One Cell Using Comma To Separate?

I have a data set that I wish to look up the data from one column and if it is greater then 0 write it in another column separated by commas. Here is an example:

The data is dates that a service was provided and how many time that day it was done and not everyone gets the service on the same days. I would like to summarize the days of the month that service was provided not number of times into 1 cell.

A B C
Row 1 November
Row 2 1 5 15
Row 3 1 0 2
Row 4 0 1 3

November is in A3

If A2 is greater then 0 I want to write A1 A2 If A2 and A3 is greater then 0 I want to write A1 A2, A3 If A2 is 0 and B2 is greater then 0, I want to write A1 B2