Sounds a possibility. Have the blisters crusted over? The dry form is not normally fatal but the wet form can block the throat, making breathing very difficult. Might be worth having a word with your vet - a/bs in the water may help. If it is fowl pox it can remain in the environment for years, so I'd isolate her and disinfect everything she's been in contact with. Keep a careful eye on the other birds.