Sudden Confusion. Then weekly once and!

For the past 2 months once in a week I felt an episode of sudden confusion with mild nauseating sensation and this just lasted for few seconds to 1 minute and then I recover to normal. Sometimes a mental fatigue even after the episode lasts for half an hour and I become completely normal. I was completely conscious during that episode but still I feel sleepy tired confused and can't think or speak or concentrate at that moment and it take few minutes to concentrate again. Before the episode occured weekly twice then weekly once and thankfully now occurs only biweekly but I am still afraid what may be the problem. Only this recent episode I felt mild heaviness in my left head region at scalp during that episode like spasmbut I don't know they're linked or its normal. Kindly say what it is. I am just 25 years old.