it`s normal after a while not to have any more periods once you are taking Cerazette
Sometime you see small cysts in the ovaries when on Cerazette - these cysts usually disappear - and in about 99/100 cases they cyst will have disappeared within 6 weeks.
The sharp pain
might be coming from the cyst - if it gets worse go back for another check even if the 6 weeks haven`t past.
You shouldn`t ovulate anyway when you`re on Cerazette. That`s how the pill works. It will stop you ovulating.
Most small cysts do not carry eggs - but just in case I would suggest using extra protection until you`ve had your check.