You probably ought to just suck it up and ask the doctors to test you. If they're making you feel bad about looking after your health, they're not good doctors, and you should try to find another doctor, if you can. I think a lot of us understand what it's like to be accused of hypochondria, or to think others suspect us of it, but it's better to know than...
Your mom might want to find a different doctor, if she can (or was it your mother who didn't think the test was necessary? I couldn't tell). Also, she can try going gluten-free to see if it helps, but if she wants to be tested, she'll have to still be eating gluten, or the test will return a false negative.