I would suggest taking him to a Dr, you don't HAVE to give him drugs and not all Dr's are like that, i think if you can find a cause for the issues then you can look at natural methods to help control it or atleast it will give you more of an idea as to whats going on.
You may even like to see a naturopath, they could possibly help!

I hope it settles soon for you, sounds like your doing all the right things but it's prob best you get it all checked now b4 bubs comes along. You never know having a little sister might just calm him down.