Parse & extract multiple recurring values from a string

Hello and thanks in advance.

I have searched and searched and can't seem to find a simple solution to this problem. All help is appreciated.

I have a column where each cell contains data that seems to be xml. Each row's cell data looks similar to this:

Please Login or Register  to view this content.

What I want to do for each cell in each row of this column is find and extract the unknown string variable between each instance of:

Please Login or Register  to view this content.

and

Please Login or Register  to view this content.

and make make that a header name for a new column IF that column does not yet exist.

Then I want to find and extract the unknown variable string between:

Please Login or Register  to view this content.

and

Please Login or Register  to view this content.

and place it under the header column in the same row as this cell's data.

So in this example the first header would be:

Please Login or Register  to view this content.

and the first value under that header would be:

Please Login or Register  to view this content.

Essentially I'm having a problem learning how to parse xml data in multiple cells and place it in their own columns and rows

Note: In my spreadsheet the first row already contains header names.

Note: the next row down would contain the same header names but have different values associated with them.

Note: I have no way of knowing how many header values will exist before I run the script.

Thankyou.