D.P.
I'm not a big fan of all of the switching, switching, switching of formulas. Do not attempt to give him plain water or anything else until you talk to your ped's office. I just wanted to say that the nurses there are VERY used to getting calls of all kinds form moms...you should never, ever, EVER hesitate to call them with ANY & ALL questions you might have. That's why they're there!
Warm baths may help.