Re: In the following days (comma)
In your title, you remembered to use the word "In" at the beginning if the phrase but in your actual post, it has vanished. I would probably have said "Over the next few days ...".
Originally Posted by Mad-ox
There was no need to put the first three words in capitals.
The comma is correctly used.
Remember - correct capitalisation, punctuation and spacing make posts much easier to read.