First thing is to figure out why she's doing this to herself. Reasons why chickens peck themselves usually have to do with discomfort. That area either itches or is giving her pain. Chickens peck at the spot that hurts, literally pointing to what is giving them discomfort.
So she's telling you to examine her carefully for lumps that could be a tumor, irritated skin that could be from parasites, or an infected wound that is festering and infected, causing a lot of pain.
Look her over, parting the feathers to see if there are lice. Check the coop at night to see if coop mites are crawling up her legs and feasting on her blood.
Check the wound for signs of red skin and pus where the open sore is. That might indicate infection that might require an oral antibiotic or at least a topical antibiotic ointment in addition to the Vetericyn.
The open wound should be flushed daily with saline and kept moist with the antibiotic ointment. Don't allow it to dry out as that will slow healing and encourage bacteria.
You can give her an 81 grain chewable aspirin twice a day for pain control. Trying to get her to leave the wound alone will be a challenge, but it's likely she won't mess with it if it stops causing her so much discomfort. Getting any incipient infection under control will usually eliminate any pain.