My guess would be seborrheic dermatitis rather than perioral dermatitis. I would use a dandruff shampoo such as Nizoral every day in addition to hydrocortisone twice daily until it gets better. Once it's better then keep using the Nizoral about twice a week to keep it from coming back.

the nizoral shampoo has been very drying on my face... what moisturiser would be suitable? or should I just leave it

Ask your doctor to prescribe Nizoral or Taro (Ketoconazole 2%) cream. Or you can buy this cream without a prescription from India without a prescription at a price of $14 for a 20ml tube. If you are in the US, it is legal to import small amounts for your own use only. www.fda.gov/downloads/ICECI/.../UCM074300.pdf; see, page 9-13 of the FDA Regulatory Procedures Manual - August 2012 Chapter 9 Import Operations and Actions.