I had this one ... about 50% reduction in sense of smell (taste depends largely on sense of smell so it gets dulled). Once I found the right med it returned in about a month (though one scent, skunk [the animal, not weed
] didn't come back until 1 1/2 years later - which is both funny and amazing).
The medical term for reduction in sense of smell is
Hyposmia. People often experience this from simple things like sinus infections or allergies. But neurological problems
can be involved - for example, loss of smell is one of the earliest signs of Parkinson's disease that occurs years before any other symptom [don't worry, it is highly unlikely that you would have PD].
Given that your symptoms started with marijuana, look into the symptomology of HPPD ... even if your visual perception is good. DP and DR are symptoms of HPPD. About 30 to 50% of people with HPPD symptoms have problems with dopaminergic neurons and respond very favorably to meds that increase dopamine. This was my case.
Good news is that this very often reverses (is not permanent), and you have only been suffering about 3 months(?). And half of those with full-blown HPPD get better on their own.
Reading your posts it is clear you are worried. But if what I hypothesized above is true, you have some of the best chances of getting better of any on the forum.
It might help if you list all your symptoms. Also, if you wish I can further describe the physiology of dopamine and how it affects the cerebral cortex.