I suspect this is fowl pox.
does it look like this:
https://www.backyardchickens.com/LC-diseases-AvianPox.html
Only, you're seeing it on the tips?
If so, it's a virus. You shouldn't treat with antibiotics as they will not help and only will hurt. However, you can and should dot all the scabs with iodine. On the ones near the mouth and eyes, use neosporin ointment and monitor carefully. If you see any birds without the "dry pox" (the scabs) who are lethargic, check their mouths inside and rule out cheesy stuff on the roof of their beaks. If you see the cheesy bits, then it's "Wet pox" which is more serious.
The article above outlines some information.
From my experience, the sooner you can remove the scabs the better. Also from my experience they're nearly impossible to remove. You can try dotting them with the antibiotic ointment (after the iodine dots) to try to soften them. Or a dot of hydrogen peroxide (again after the iodine) if they're not near the eye. But otherwise continue to dot the sores every other day or less, monitor for any secondary infections.
It's very important to boost these birds' immune systems so that they heal better. Give them their best clean fresh laying feed. Vitamin A and E are very helpful to healing. You could mist "Fortified Wheat Germ Oil" (marketed for horses, read the label for A, D, E fortification) onto their feed daily for a week and then thrice weekly for the following three weeks of infection. The A will help combat any problems with the sores hitting their mucus membranes (eyelids, mouth, nostrils). The vitamin E helps reduce inflammation and heal through anti-oxidants. Boosting their nutrition in this way can be very helpful to full healing.
Expect it to run for four weeks. It's spread via insect vector (biting bugs like mosquitoes) and scabs. Once some in the flock have it, they all are exposed. Some will not show symptoms. Using the immune booster will reduce symptoms and thus damage d.t. the sores. All birds will be immune once they're over it. They then will shed their sores which are also infective. If you use bedding, discard the bedding once they're all through if possible.
Watch carefully for pecking as you know how chickens are. give them something else to pick at - granite grit and a hung cabbage head for example.
I hope this helps. Please let me know how I can be of any further assistance. Thanks!