when one Citta perishes,from where does the next arise?

Anatman/Anatta says that the 'self'is a momentary flux of Cittas-Vijnanas.There can be no stable permanent Citta,in kshanabhangavada a dharma perishes before its successor arises.one citta arises then perishes and another takes its place all going on until Nirvana is established.However,when one citta perishes,from where and what does the next Citta arise?it cannot be a nothing.but the Citta also cannot preexist as that would be absurd and there would be infinite mes or yous right now somewhere.it would also mean that the world would be Fate.but such a notion is Absurd anyway.it cannot also be that there is an infinite set of predetermined Cittas in a dormant state.as Cittas are all that' Exist' in the Mahayana and Tibetan schools.They cannot be dormant.dormant where?in a concrete external world?if such a receptacle existed wich was permanent and unchanging and not momentary it would be a Self! Citta can be equated with Vijnana Skandha or alaya vijnana aswell,as the alayavijnana is momentary within Buddhism. it cannot be that the Citta has the same substance as the former Citta because then it would just be the same Citta and Cittas are not Substantial according to Nagarjuna. It cannot be that a Citta endures until the next arises because this would confer confused Experience and still the former Citta has no Causal power to create another Citta Exnihilo. So how does the momentary flux of Cittas work?