I assume the picture will take a while to show up so I'll try to describe it. A bit over two weeks ago DD pulled a bit of loose skin off her finger on the side of the nail, it then went a bit red and was hurting, I made her clean it well, put some antiseptic cream on and told her to make sure it stays clean. Over Easter it was hurting more and some pus came out and was still red and hurting last Tuesday when she had an appointment with the school nurse for another reason, showed it to the nurse who said it was looking OK and just to carry on keeping it clean and dry. She's been keeping a plaster on it and telling me it was OK and getting better but last night I saw it and it was much more red and a bit swollen and just generally looking much worse.
I told her she needs to go to the school nurse tomorrow because it made need antibiotics now but she is 14 and refusing, saying its feeling better 
but surely if it got better and then worse again it's not good and needs seeing? I can't exactly force her at this age (in my country at this age they can mostly make their own health decisions) but I can probably persuade her with enough evidence.