Hi Jane....so sorry to hear of your boy's problem.
I can fully sympathise, having been a sufferer from Eczema myself, mainly as a youngster, but still get an occasional flare-up.
Yes, the first port of call must be your Doctor, who will give you an appointment with a skin specialist if he deems it necessary.
Try to keep your boy cool (avoid hot baths), as the salt in sweat really doesn't help.
Try using natural fibre bedding...ie 100% Cotton, and same with clothes next to the skin.
Pay careful attention to his diet....plenty of fresh fruit and vegetables, and be very careful about chemicals in soaps, washing powder, shampoos etc.
Use mild ones natural ones.
Some people with Eczema can be sensitive to dairy products...particularly Cow's milk.
Try using Goat's milk...available in supermarkets now.
You don't state the age of your child, but young skin is pretty good at restoring itself.
Keep his fingernails cut very short and use a moisturiser rather than greasy cream on the affected areas.
Also have a think about any stress there may be in his life, as this can worsen skin conditions too.
Often (as with myself) the condition improves or disappears with age.
Personally I wouldn't start wasting your money on unproven herbal remedies.
Providing he's given a healthy diet, (plus some sunshine and exercise) the body will sift out for itself what is required.
As far as I'm aware there is no known 'cure' for the condition.