maybe some more info will help. male/female? Excuse for what (forgot the assignment, slept with his daughter by "mistake", stole his money, trashed his laptop ect.)
maybe something like: "Sorry, but we both got some alcohol + drugs, but I love her very much and I will take the responsibility for her and our child so don't worry..."
Professor whatever, Sorry I cannot attend class today due to headache and running nose. I do not know what is wrong so I made a doctor's appointment today for a checkup.Blah, blah
Get a signed doctors note stating specifically that he suggested that you stay home and recover that day from blah blah blah...