There is chance you have a sinusitis
problem which is making you light headed & sleepy & causing you to have loss of appetite. then further weakness due to inadequate nutrition making you feel dizzy as result of vicious cycle.
I would suggest you to see an EarNose Throat doctor & have a PNS xray done to rule out sinusitis.
Till then you might have a Sinarest/ Fenoxifenadine/Cetrizine/Levocetrizine I tab empty stomach per day with steam inhalation. But do see an specialist.