REGULAR CHECK UP
As on your first visit, a doctor may not be in position to diagnose finally, he may have few differential diagnosis. He has prescribed a medicine for a most possible cause of your complaint and not for all.
So your second visit may help in clinching diagnosis. A self praise for a doctor, which he genuinely needs. There are other conditions where you need a periodic check up for prevention rather than cure.
And lastly all post surgery periods need a regular follow up and added instructions from your trust worthy doctor! So, say yes to regular check up, it helps you more!