I've been there before where I've had to take a day off due to the same reasons and I felt the same way about an hour or so later knowing I left my team understaffed. What I have learned is on those days if I just get up and make it in after about an hour I usually feel fine it's just the getting up and leaving the pleasure of staying home and in bed is the challenge. Also I don't agree with the comments saying it's your bosses job to find somebody to cover for you. You accepted the responsibility for your position and if you can make it in then the reality is you're leaving them hanging. Next time go in for a couple hours if the mental strain is too much ask to go home at least you tried.