scratching head

Hi mamas! My LO is 7MO.. He likes to scratch his head and tug his ears and shows signs of irritability. Once he tugged his ear so hard that there was a blue black mark on it. He's been doing this since about 3 months old. I raised the concern to a PD before but she said it could be because of the eczema. Yes my son has eczema but his head has no bumps or anything. It's very smooth.. I read some article they say it could be ear infection but my son doesn't have and discharge from his ear.. Any mamas LO's doing the same? Should i be concerned? Or is this normal and he'll grow out of it?