With the modification of a single line you could alter the fullcalendar.js script to allow a line break and put multiple information on the same line.
In FullCalendar.js on line ~3922 find htmlEscape(s) function and add .replace(/<br\s?/?>/g, '
') to the end of it.
function htmlEscape(s) {
return s.replace(/&/g, '&')
.replace(/</g, '<')
.replace(/>/g, '>')
.replace(/'/g, ''')
.replace(/"/g, '"')
.replace(/\n/g, '<br />')
.replace(/<br\s?\/?>/g, '<br />');
}
This will allow you to have multiple lines for the title, separating the information. Example replace the event.title with title: 'All Day Event' + '<br />' + 'Other Description'