Shortness of breath. chronic dizziness. always tired. had mri head x-ray chest stomach cbc ekg all normal. i'm 25 and doc says i'm fine. i hate this?

Easy-to-miss stuff: Trust ANA thyroid calcium B12 syphilis bloodwork normal, no fad diet or arsenic; depending on big picture, easy-to-miss items include pulmonary hypertesion, parasomnia/restless legs, sleep apnea, carbon monoxide in home, myasthenia gravis, porphyria lyme. Physician may consider trial low-dose ssri and/or offer trial of intensive aerobic training. Good luck.

Need to examine: It is not feasible to provide a meaningful opinion without taking additional history, physical examination and may be some tests. It would be prudent to see your doctor and discuss if you may be depressed. Counter-intuitive as it may seem, exercise may help. Start with low intensity exercise such as walking and gradually increase the intensity as tolerated.