hi there
it is quite common for babies to get really unsettled etc. around the 3 - 4 month age. They usually go through a big growth spurt and their whole routine just goes out the window.
My advice " It is a phase and he will get through it".
No consolation I know, but it will pass and he will settle down again. Meanwhile, its bury the hatchett and wait for it all to pass.
Good luck!
Just when you work out the buggers - they go and change on you!!!