The flakey nostrils problem is probably caused by a mixture of excessive bacteria and fungus in the nose mucus which has been caused by a weak local immune system. This means that the immune system neutrophils and eosinophils in the nose mucus -- acting by immune phagocyte action -- are somewhat weak and lacking in their immune defence. 

What I would therefore do is thoroughly disinfect the nose and nasopharynx region behind the nose(which is also an untouchable and unreachable breeding ground where bacteria and fungus can safely hide away from the immune system and drugs) using a neti pot containing water + 1 level teaspoon of baking soda(Arm & Hammer brand is OK to use) + two drops of lugol's iodine. Do this once or twice a day. This will act to safely disinfect the nose and nasopharaynx area to successfully and completely clear this region of the pathogens which seem to be dominating.  

It is also apparent to me that your immune system is not as strong as it should be. Therefore supplementing other immune-boosting nutrients like Colostrum(Sovereign Labs brand) and/or Carnivora should also substantially help to boost your immune system so that your problems don't come back. I'll leave you to do your own research these nutrients.