most doctors prefer one or a lesser number of diagnosis..
from the description, they do appear to point to one abnormality in your brain that causes a number of things in your body..
first of all, classic migraines improve in a dark, quiet and slightly colder room..
if you have headaches from migraines, put yourself in a dark, quiet and slightly colder room with no TV, no smart device, no music, no lights.. just sit or lie there quietly for 10-30 minutes and you should see quick improvements in less than an hour..
silent migraines is when you have the symptoms of the classic migraines but without the headaches, such as visual splotches or spots (collectively known as Aura) and they too improve by remaining in that dark, quiet, and slightly colder room for 10-30 minutes..
next Silent Migraines is a form of seizures..
we often associate seizures or epilepsy with falling on the ground and shaking uncontrollably, but there are several types of seizures that are very similar to Silent Migraines, of having Aura only without the main symptom.. but unlike Silent Migraines, the aura in seizures is often associated by a sense of sudden unexplained mental exhaustion - the Aura in a way would drain-out all your mental energy..
the Thyroid gland (located in the neck) is influenced by the Pituitary gland (located in the brain in an area called mid-brain).. an illness in the brain could activate the Pituitary gland to stimulate the Thyroid gland production.. when you test for the Thyroid gland, we often test for T3 and T4 levels (the levels of the Thyroid gland production) and we often test for the TSH level (the level of the Pituitary gland production)..
if you have high levels of T4 and/or T3 levels in the blood, it is called hyperthyroidism, but if the TSH is high, it means that the cause for the hyperthyroidism is an illness or a disorder in the Pituitary gland deep inside the brain..
similarly, if you start to have visual symptoms, the cause could be from the eyes, from the Optic Nerve that runs from the eyes to the brain, or from the brain itself involving the Occipital Lobe (the back of the brain that handles vision).. but since your eyes (your Retinas) look fine (beautiful), the problem could be at the Optic Nerve that runs next and inside the brain, or at the Occipital lobe that interpret vision..
in short.. they all point to a problem in the brain..
and the MRI of the brain remains one of the best non-invasive investigative tool to the examine the brain.. it is indispensable and it is valuable to zero-in to a working diagnosis.. and.. to exclude other diagnosis that are rare, sinister and harder to manage (from aneurysms to tumours (both benign and malignant types)) - again those are very rare conditions..
another possibile diagnosis, is visual hallucinations caused by acute mania secondary to hyperthyroidism..
in this scenario, the main culprit is the Thyroid gland that indirectly cause the abnormal colours in your vision..
the Thyroid is the control-centre for a power-station.. it decides whether the cells all over your body should go at full throttle and at full consumption of energy; or the other way around.. this is why in hyperthyroidism, patients become active, anxious, more irritated, and having tremors and losing weight faster, this can activate acute mania with visual hallucinations.. it is a bit far fetched but not entirely an impossible scenario..
the main symptoms of mania: fast talking, having too many thoughts at once (racing thoughts), setting too many goals (trying to do many things at once), taking few hours for sleep (because of having too many thoughts and too many things to do), and occasionally having visual and auditory hallucinations..
managing the hyperthyroidism should help in mania and in hallucinations, if this is actually what is happening..
good luck, God bless and all the best..