One possibility you could check out is Celiac Disease
. It causes nutritional deficiencies, and as such it can cause problems to every part of your body, including your brain - depression
is not uncommon.
Being accused of being depressed or having it 'all in your head' is also, sadly, not uncommon.
A gluten free
diet is the closest to a cure for the disease, although if you wish to have a diagnosis from a doctor, you will need to wait on that until you get in to see a doctor, as the test can't test for anything but your body's damage and the reaction to it. Once you start to heal, the test is useless unless you damage yourself again with gluten.
This is a list of the many symptoms that can result from Celiac Disease, to see if they match your experience: