Hello, Welcome to Just Answer and thanks for your question. Actually, you can. Dermatitis herpetiformis is caused by an allergy to gluten. This allergy can also cause symptoms in the digestive system, in which case it is called celiac disease. Either can exist without the other, or both symptoms can exist at the same time.
That is too ironic! It is quite likely that you are allergic to gluten, but an allergist would need to confirm that. That is also how you confirm that it is truly DH and not some other kind of skin problem.
Avoiding gluten should really improve your DH with very little cost involved. It will cost something because gluten-free foods are harder to find and somewhat more expensive. Breads and pastas in particular are difficult to find and the texture is somewhat different from what we are accustomed to, but you can try whole foods groceries, health food stores, etc. You can often find specialty foods there that aren't in some grocery stores.
You're so very welcome.