Definitely agree with the previous post. It would be the growth spurt... both my boys did it at 10.5 weeks, so 11 weeks is not too early.
I would also not advise the rice, infact it is more likely to make your lo wake up more & be unsettled, he is much to young & intestines too immature to get any value from it... infact, you could be setting him up for lots of food related problems in later life if you did. Research shows later is better.