I agree with Stevo2. Let me assure you your frilly is not going to die nor do you need to rush it off to the vet. Why do people get on these forums and make these sorts of comments on subject matter that by their own admission they know nothing about. I have kept and bred dozens of frillies from all 3 forms over the last 20 years and I can assure you I have never seen one succumb to a damaged frill or a frill infection. At worst you may get a fungal infection that may cause a bit of discolouration, however that is not what you have with your individual. To be honest I have never had an individual present with a fungal infection on the frill (or indeed anywhere else on the body for that matter) but I would not rule out the posibility depending on husbandry. As stevo2 has already said it is quite common for frillies to have damaged frills. I have had males with virtually their whole frills torn right off, makes no difference to their quality of life in a captive environment. I had a female very recently that had so many holes in her frill from males grabbing her during mating, she still produced healthy youngsters and lived a normal life. Colour change is absolutely normal in virtually all dragons including frillies. It is effected by age, sexual maturity, mating activity, excitement, envirnmental conditions, body tempreture, stalking prey items and so on. As the animal ages the colouring changes, particularly the black splotches on the frill become more permanent, although there will be certain conditions that will see them almost disappear completely, such as cooler tempretures.
It is good you are vigilant and notice changes in your animal. It is also good that you make inquiries on this forum about the health of the animal when you have a concern. It is unfortunate though that some replies may be way off the mark and may even lead to distress for the person making the inquiry because of misinformation. As for rushing off to the vet every time you have a concern about one of the animals in your care, I wish I had a tena for every time I have seen this advice on these forums. Good luck with your frilly it looks perfectly normal and healthy as far as I am concerned.