Here are two solutions for ssi-web-6:
1) Format the question as a "grid". Edit the row/column setting, add "Day/s" to the "Cell Input Labels" field, then select "Position label 'Right' of input".
2.) If you know javascript, then call the id of the combo box (if using document.getElementById(), then don't forget "_input" if necessary... review the question html if you're unsure if this is necessary), then call the id's parentNode and do something like this:
document.getElementById('q1_input').parentNode.innerHTML += document.getElementById('q1_input')+'Day/s';