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I pray tahajjud,Dhuha, all Sunnah and Fard prayers on time, I fast Dawood Fast, sometimes monday and thursday instead, and fast white days. I avoid major sins completely and try hardest to avoid minors. I wear hijab and am polite with people, Alhmadulilah. But sometimes I feel tightness in chest and cry or feel very sad and heavy for no reason. I find it hard to study etc, can you give advice pls