What Could Cause Dizziness,tiredness,nausea And Hyperventilation Of Heart?

Good Day doctor, I am 28 years of age. During the day my left arm goes numb sometimes tingli I feel tired the whole day, I dont really eat as much as I use too, cause sometimes that also makes me feel bad. About a month ago my heart started beating fast, I felt dizzy, it felt like all my veins were closing and that I wasnt getting enough blood/oxygen, I went to the hospital and the doctor told me that I was just hyperventilating, it went away for about three days and then it just started again, but it comes and goes, I feel extremely dizzy, tired and nauseas through the day, please let me know what this could be