Alloflux, like most fluxes, is when there is a period of time when you do not identify fully with this term. It means that there is a fluctuation in your experience of this identification.
Alloflux can be used for all attraction/sexualities. It is really more up to you on how you feel it.
For example: If someone were alloflux in their sexuality, it would mean that they would feel allosexual at most times, but then there would be times when they identified more with asexual. It is enough of a change that the person in question would feel attached tot asexuality while still feel that they are allosexual.