Hi Ngala,
My little man did the exact same thing... he slept through from 6 weeks old... then at about 9 or so months he started waking up during the night with that almightly blood curdling scream!! This went on for about 5 weeks..... I was working full time at the time and was EXHAUSTED!!!
I am not sure if he was picking up on me being stressed working FT and trying to manage the housework, dinner, ect ect.... but as I said it only lasted about 5 weeks........ then it just stopped and he went back to sleeping through .

Hope that wasnt just a ramble but that it might reassure you that its probably just a "phase"
Good lukc
xoxoxo