Hello As you mentioned that once in a week you got giddiness and vomiting and a sound in your right ear. You took treatment as well as M R I with no finding . Giddiness is related with a reeling sensation & feeling as being to fall . When such type of symptoms present may be due to these reasons , these includes. 1 Hyper tension , diagnosis can be confirmed by examination at the time of incident as well for 3-4 days regularly . 2 Hypoglycemia is another most common cause . Get in blood sugar level. 3 Hyper acidity or gastritis is the another such cause.Whenever you feel such symptoms take some antacid . There are so many reasons as , tension, Minere s disease , vestibulococchlear nerve impairment . Since your age is very young so in my opinion consult an E N T and get his opinion. When such patient visit in my clinic I usually prescribe betahistine 48 mg twice in day for 10 - 15 days with pnataloc- D once in day. Hope this information will help you.