What's wrong with me

Recently my elder brother died due to sepsis I can't able to focus had a test just scored 280 I don't know I felt embarrassed I was any scoring 480sh in my tests but I dropped down to 280 though I have finished syllabus left with few chapters of physics,how to increase my marks with only 3 months left,Idont even know what to start when I sit plz help me guys I just need 600+ in neet