Extensive medical workup is what I would think is called for. Hemoglobin, white blood cell count, liver panels, kidney tests, stomach enzymes, pancreatic function, the whole works. Something is going on for you to have endured this so long.

In addition, allergy tests should be made to determine if you have serious allergies which can cause the symptoms you describe as well.

Get a good internest to start the ball rolling for you. Afterwards, if there are no
biological reasons for your feelings, see a psychiatrist, because it's going to likely
be an emotional thing then.

Psychiatrists, unfortunately, don't often do the bloodwork before they prescribe.
I think it's much smarter to have all the bloodwork done with an internist's and
allergist's authority and then submit the results to a psychiatrist if it turns out you
need psychiatric help.

The whole process is skewed by going in to see a psychiatrist before having all
the critical work done first when it's a problem with the blood or organs.