You should call the pediatrician as soon as possible. This does not sound normal.
I hope everything is okay! Update us soon if you can.
It doesn't sound like a normal toddler, take him the dr again, or even switch if you don't think his current dr is doing a good enough job.
In the mean time, try blending things and giving him "smoothie's" to drink. It's possible he may just not like the texture of solid foods, but to get him some of what he needs try blending some Yogart and fruit. Or you could even add some Yogart, sweetpatatos and Banana.
I hope things get better for him soon!
Sorry to hear this. I agree with above. All though my DD goes for days without eating much and still produces wet and dirty nappies.
I agree that she needs to see a pediatrician. There are also help lines where people come out and talk to you about different things you can do to help your child to eat. Your son may have something else going on such as a texture issue where he doesn't like anything that isn't smooth. There are food therapy classes that can help with this. I would say to try talking to someone about this asap.