It may be you need to use the steroid cream for a bit longer than you would hope to get the skin clear. Eczema Society had a brilliant article about it in their last magazine.
It explained that often people are actually not using it enough because they are afraid of it causing skin thinning. These days they actually see more children with thickening of the skin from under use than thinning skin from over use.
Also putting on the hydrocortisone straight after a bath means it works better as it penetrates the skin more.
I think it would be helpful if Doctors could actually SHOW you how much to use and this is where a referal to a dermatologist or skin nurse at hospital would help.
I'm not a big fan of Oilatum, ask for something else especially as skin infections can be a major problem if the skin is broken.
We've only ever seen our GP, but it helped that he had a special interest in eczema as his DD had it.
I know it's awful, but they often do grow out of it. This time last year my DS had huge red patches in his arm and leg joints and round his neck and wrists and looked like he was wearing red socks his feet were so bad. He also never slept through the night because of the scratching. It all just made me want to cry and sometimes I did.
His skin has got loads better over the last couple of months and life is very different for us both.
They can grow out of it and I hope your DS will hurry up and do the same!