R.M.
Poor baby and poor mama! I hope you take him to the doctor asap. Try a medicine syringe to get some pedialyte into him (Walgreens / RiteAid sells them if you don't have any at home). Just suck some up, gently push it in to his mouth on the side and squirt it into his mouth. That way you are getting something into him without asking him to do it. I hope he feels better very very soon!