Why I Keep Getting Nausea And Headaches ?

hi, my mpv is low, i have tachacardia with low blood pressure , chronic fatigue for years, dizzy, light headed at times, pain inside legs and arms, now in hands, major mental challenges, sometimes chest pain , numbness or tingling. 28 yrs old, 5/2, 110lbs, always been thin, shortness of breath nausea and headaches when i was a child which went away, came back as a teen, then went away and back again during pregnancy, getting worse. Chronic laying down (going insaine bc im a thinker and want to do so many things n have so many ideas but feels like im pushing heavy metal or against magnets to do anything) unless taking major stimulant medicine.