Depression can do weird things to a person. My husband is going through something similar. His is due to something in his past, but stress and depression alone can cause these problems. My husband has a conversion disorder. He can't use his legs at times, he has stroke like symptoms, weak and tired always, passes out almost daily, and he also has stomach pain. He has no control of any of this, and its not "in his head". Depression and stress just somehow miswire the nerons or whatever in the brain and the brain tells the body it is "sick".
It is important though to first have a physical doctor to rule out all medical possibilities. One test I reccomend you bring up to a doc is a tilt table test. they strap you to a table then stand you up and monitor blood pressure and heart rate. You may have Postural Orthostatic Hypotension. This basically means that blood pools in legs upon standing and cant get to the heart and brain fast enoug so you faint or near faint. Hope this helps.