Contacting doctor regarding PPD

I sincerely believe I am suffering from PPD. I am 4 months postpartum and ever since I had my daughter, I have been feeling miserable. Getting through the day has been a challenge. I need to make an appointment to see my doctor but what do I say to front desk when I contact to schedule an appointment? This is something I am ashamed of and I don’t want people to know I am going through this.