Sorry for replying a little bit late.

Actually, the Aircraft was in a safe speed and the angle of attack is not very high. Every time I takeoff, I would pitch up the nose at around 5-10 degree to maintain control of the speed. And also one thing I also forgot to tell you that when this thing happened, the auto-thottle won't work either. I even tried testing the autopilot while leveled in flight. Speed is 235 kts and I switched on, and the aircraft starts turning left and right and the nose pitched up to a dangerous angle (50-60 degree) and stalled and I wasn't quick enough to save the aircraft.
SO CAN YOU FIND ONE SIMPLE SOLUTION FOR THIS PROBLEM?? ANYBODY??!!! :(