So I remember a time last year when I got pretty sick and stopped smoking. I thought "my throat cant handle this so no more cigs or weed"
It hardly helped. I felt like shit because I wasn't getting better. I finally started toking after 3-4 days and I swear it made things 1000x better. I would occasionally have an hour or 2 after smoking where I wouldn't be in pain, congested and coughing.
Since you have mono, you're guaranteed to be out for a week, possibly 2. Don't sit around all day and smoke, but it will probably make things a little better if you smoke a bowl every other day or something.