Self harming 14 month old (rubbing his leg raw)

TL;DR - My 14 month old fraternal twin boy rubs the back of his knee with his foot until he bleeds. He's been doing this for 9 months. The pediatrician just gave me steroids to treat the wound. Is this behavior normal and what can I do to stop it?I've got 3 kids, a 2.5 year old and 14 month old twins. The problem I'm having is that my boy twin has ongoing self harming behavior that has me concerned, mostly due to the longevity of the issue.My oldest went through a brief head banging out of frustration stage when he was between 9 months and a year old. He outgrew it pretty fast and never tried to do any real harm to himself. My daughter has only banged her head a couple times, lightly, copying her twin. This is a recent behavior, and pretty normal, as far as I'm aware, but this leads into the start of issues with my boy twin.My boy twin started the headbanging behavior in his high chair at about 5 months old. He would do it constantly and quite hard - to the point that the high chair, even with all four wheels locked, would move across the kitchen floor. We resolved this issue by putting some thick foam behind him when we became concerned about the bump he was giving himself. He still tries to headbang (9 months later), but doesn't get anywhere with it and can't hurt himself with it. This doesn't concern me that much, though I am a bit bewildered by the dedication this kid has to hanging on to the behavior. This mostly seems to happen when he's bored or frustrated.The bigger issue is that starting from when he was about 4 or 5 months old, maybe even earlier, my memories from that early are very hazy due to sleep deprivation, he's been using the top of his right foot to saw away at the back of his left knee. He does this pretty much every time you have him on the changing table, in his crib, whenever he's upset, frustrated, bored or just generally not being entranced by something better. He will rub that spot until the skin is gone and he's bleeding, and he will continue to rub. I've brought this up a couple of times with our pediatrician, but they just gave me a prescription for steroid cream - treating this more as a physical issue than a behavioral one. The cream will get the spot to heal, if I actively keep him from rubbing for a week or so, but all it takes is not being right on top of him once and he's got it open and weeping again. This has got to hurt and it's causing a chronic open wound that has lasted more than half his life at this point. I understand with most behavior like this in kids, they won't keep hurting themselves in any real way - he is. He also seems to be going through a phase recently where he likes to gag himself, but that too, I believe, is reasonably normal.He's a little small for his age, but was born early full term and is hitting all his developmental milestones normally or slightly ahead of the curve (as are his two siblings). I am concerned that this behavior doesn't seem to be something he's growing out of and he's causing real harm to himself. Is this just an extension of the head banging? Is it normal and do I need to ignore it or is this indicative of something I should really press my pediatrician about more? Any advice on stopping him from hurting himself would also be greatly appreciated. (I've tried band aids, I've tried gauze and stretchy wrap, I've tried no shoes, I've tried no socks, I've tried only soft pants, I've tried shorts, I've tried combinations of all of the above, none seem to be a good long term solution)Thank you. via /r/Parenting http://ift.tt/2qgQTRI