Yea I went through the same thing with the specialists. They did say my daughter could have an endoscopy but they didn't think they would find anything, I decided against it. My son doesn't have candida but he did suffer from constipation from being a baby. Diet and more fluid helped him but didn't help my daughter, I think the Antibiotics had caused too much damage with her. I think I'd take saywhatagain's advice and start with the diet idea's, sounds like a safer option for children so young. This might be the turnaround you need especially if funding is a problem. I'm in the UK and the NHS pays for tests etc. I did pay privately for the herbalist though and so glad I did.
I wish you good luck. I know how much stress you are under but you will get through it.