Help!!! My baby won’t stop scratching himself!

I need help!! My son is 7 1/2 months now, since he was 3 months he developed an insane scratching problem out of nowhere and it has consistently gotten worse over time. We’ve tried so many different things, we don’t know what to do at this point.

So it started at 3 months, we took him to the DR. and dermatologist and found out he had eczema, so we started switching lotions and body washes, also started oatmeal baths and bathing him much less, the eczema would clear up sometimes, but it didn’t matter, the scratching wouldn’t stop. He would even do it while sleeping and rubbed bald spots into his head!!!! Some of which have not grown back. We have to put him to sleep with a sleeve or mittens on.

Fast forward to 6 months old, we took him to an allergist and found out he’s allergic to milk and eggs, so we switched him to Nutramagin, the eczema cleared up but he still scratches like crazy. We also changed detergent to All Free and Clear.

I’ve noticed that he mostly scratches at bedtime, when he’s tired, or frustrated. He scratches his head, behind his ears, chest, stomach, hips, and thighs when I’m changing his diaper. Sometimes the scratching is violent. Every day is a struggle, I literally have to hold his hands down to stop him and he goes crazy. I’m at my wits end, don’t know what to do. Has anyone ever had this experience before??? I will try anything, please help!