Both my sons went through this and unfortunately they had to do so multiple times. It is tougher on you than on them. Both my sons recovered very quickly.
My sons were born without enamel on their baby teeth, so they rapidly decayed. Do you know if that's the case for your 3 year old? If so, it's imperative that you be tested for celiac. It turns out that because I was undiagnosed during pregnancy, I was not absorbing enough of the nutrients (i.e., vitamin D, calcium, etc.) necessary for the fetus to develop tooth enamel (baby teeth are formed inutero). The body will sacrifice the enamel on the teeth to build bones, etc. Fortunately, my sons permanent teeth were okay.
You can ask your PCP to run a celiac panel or you can get tested on your own:
www.enterolab.com
I cannot urge you enough to have this done, as celiac is genetic and it is the MOST highly undiagnosed genetic disorder in this country. The reason being that the treatment is purely a dietary change (no wheat, rye, barley or oats) and there is no Rx med at this point. I can guarantee once there is, that every doctor will be screening for this. It turns out both my sons have it and it was 7 years after we started dealing with the dental issues that they and I were diagnosed. I would hate for someone else to suffer in the way my family did.
You can also be asymptomatic and still have celiac and have the issue with nutrient absorption. You don't say how old you are, but I was 42 when I reached the point of the symptoms really being overt.