Many stubborn skin issues can start from what we eat. More specifically, what lies beneath our stomachs in the digestive system.
A lot of skin issues can start from an imbalance of the good and bad bacteria which populate the gut. There are many millions of neurons in the stomach lining that talk to the brain and what goes on in the stomach and gut, also has an influence on the immune system. The main problem-creators are things such as heavy carbohydrates, sugar, caffeine, alcohol and over-processed foods. It is already widely known that what you eat, drives skin issues such as dermatitis, acne and eczema. If the stomach and gut cannot get rid of toxic substances, then those toxic items are sent straight to the skin.
Inclusion of probiotics in the diet helps significantly. These are the "good" bacteria, that break down foods and support the immune system and it is very important that we maintain the right balance between good and bad bacteria. That said, if there is nothing wrong with your gut and digestive system, through a varied and healthy diet, then you don't need probiotics. Many of the mainstream "supermarket" products advertising probiotic content do not really hold enough of the good elements as you are really looking for about 40 billion or so live cultures from about 10-15 different strains. Either way, it makes sense to have a professional diagnosis if you have skin issues which may be digestive tract related.
Digestive system friendly foods include fermented foods, such as Kefir (a fermented milk drink which you can now find in many supermarkets, if not then visit a local East European food store) and sauerkraut; healthy fats such as coconut, avocado and fish oils, tomatoes and green tea and (seeing a resurgence) is bone broth which has origins deep in the past as it is rich in minerals, collagen, gelatin and cartilage.