Hi, and welcome to these boards.
I am sorry to say that you have a very ignorant doctor, who tortured your baby with taking all that blood for nothing. First of all, those tests are extremely unreliable in children under six to begin with, and secondly, after being gluten-free for a whole month, you are guaranteed a false negative, even if it would have been positive a month ago.
Since celiac disease is not an allergy, the skin prick test wouldn't show it anyway. That was to be expected, unless Tommy is allergic to wheat on top of having celiac disease.
For Tommy, the one test that would still be accurate in showing if he is gluten intolerant, would be the one from
Enterolab. They test the stool, so no more torture. This test is the most accurate one available, even though it isn't cheap.
I would switch doctors to have the other kids, your husband and yourself tested. After that, I would just make the whole house gluten-free!
I hope it all works out for you. I am glad Tommy is feeling better on the gluten-free diet, keep up the good work!