Perorial dermatitis, please help..

My son has been suffering with dermatitis for around 3 months now. The first 2 doctors I saw prescribed steroid cream as they didn’t diagnose it properly which made it worse. The 3rd doctor I saw prescribed a cream for the rash which temporarily helped it but not fully. 

These past 2 days it has really flared up and spread quite badly, I went to the doctors today and for prescribed adex gel (only just recently come out) to help. 

I was just wondering if any one else’s LO has suffered with this as it looks so bad at the moment and sometimes he tries to itch it. I have heard about calendula cream and ordered some if this gel doesn’t do anything so if anyone has any experience with that as well I’d love to hear about it!

Any advice would be really appreciated as I feel like I’m failing and fighting a lost battle  

Thank you.