Are you working with a complementary or DAN! physician to address the base of the immune reaction? They would be doing things like IGG testing to find if he is reacting to foods (digestive is the main immune organ), treating for yeast or bacteria, supporting the body with supplements, etc.
Is he on medication for the asthma? The reason I ask is that often the medication has the side effects of hyperactivity depending on the base of the medicine.
I use netty pots very effectively with my kids. I add a chinese herbal compound called Neti Wash Plus (Varcho Veda) which tends to open the airways and flush the congestion. However, I am not dealing with asthma.
I have heard Rescue Remedy (a homeopathic compound) is good for calming, but it depends on what is causing the hyperactivity. Gaba and melatonin are both used for calming as well.