My granddaughter was diagnosed with eczema when she was just a few months old. She's had impetigo but not psoriasis. She also has asthma. She is also a happy child who sleeps well and seems comfortable even tho she is scratching almost all the time.
Do you know that impetigo is a virus, I think. Anyway, it is something that you get when you're exposed to the "bug" and has very little to do with the skin's condition. Just like any cpntagious condition one is more likely to "catch" it when one's resistance is low. If the skin that broke out with impetigo was already compromised I suppose that she would more likely break out than if her skin in that area was in good condition.
Just FYI, my cousin treated a skin condition on his legs that was diagnosed by more than one doctor as psoriasis. A few years ago a new doctor told him it was a yeast infection. He treated it with an anti-yeast medication, it went away and has not returned. Diagnosis and treatment can be a matter of trial and error.
My granddaughter has been tested by a pediatric allergist and she is allergic to milk, soy, peanuts, as well as animal dander, grass and tree pollens, and perhaps some other things. Her reaction to these allergies has more of an effect on her respiratory system than her skin. She also takes Zyrtec.
It is my understanding that eczema is either triggered by a skin irritant or caused by a difficulty with the skin's composition. The skin of someone born with eczema has a more "rough" texture and is especially dry. Her skin does feel different now that she's older. It's still smooth but not as soft. As a baby her skin was smooth and soft just like the skin of a baby without eczema.
One can get a different kind of eczema (contact dermatitis) thru exposure to skin irritants such as soaps, detergents, scents, etc. Because my granddaughter has chronic eczema she has to use gentle cleansers with no scents. When she was a baby her mother used mild laundry products without scent. I do wonder if she returned to using the mild no scent cleaners if my granddaughter's skin would be less irritated.
Both eczema and psoriasis can be controlled with appropriate skin care which can take a lot of work. My granddaughter's eczema is often "out of control" (red itchy patches on elbows, knees and various other flat areas of skin) because at 8 she doesn't care what her skin looks like. She hates lotions and resists applyiing anything to her skin. However, once the rash is bothersome enough she does use the cortizone cream and prescription ointment. If we put the cortizone cream on the flat skin areas once we notice the rash (this is OK with her) the skin clears up in just a few days: sometimes in just a couple of days.
I sympathize with your worry but I don't know how to respond to "obsessed." Is part of your obsession about using the cortizone? My granddaughter has been using steroid creams and ointments off and on for nearly her whole life. Yes, they are not good to use constantly but if you use them as prescribed you will only be using them for brief periods of time. Most skin conditions clear up quickly with consistent short term use along with good skin care.
I have mild acne rosacea (reddened skin with some infrequent breakouts on my face) and so have frequently used hydrocortisone but only for a few days at a time once the breakouts were under control in my 20's. (I didn't have acne as a teen and thought it was totally unfair to start in my 20's. :):) )
Remember that medical sites have to be overly cautious when they give warnings. My doctor explained about the strongly worded warnings by telling me that a large group of people do not follow directions. Some say, "if a little bit is good, more is better," and continue to use the cortizone for weeks which will then worsen the appearance of their skin. Cortizone applied to the skin over an extended period of time thins the skin.
I also take cortizone orally every once in awhile for conditions that do not resolve with other forms of treatment. I never have to take it more than a couple of weeks and thus am not in danger of the negative side effects cited in the literature.
Once you know what your son's skin condtions are and how to treat them your life will become "routine" again. Since he's a happy and sleeps well he will be alright. If you continue to be worried and obsessed he will pick up on your anxiety which has the potential of reducing his relaxed way of being and thus increase the possibility of more frequent break outs and discomfort.