Cough, Cold and weakness. Weakness ever.

Before 1 week I had cough,cold and fever for 2 weeks in which after 7 days I was getting blood in sputum(phlegm) then I thought to have check up for it but when I went to hospital they said they need thick greenish sputum for test but I wasn't getting that and they did blood test too but report was normal.After 2 days blood was reduced and Phlegm was also not coming more so I dropped the idea of test and after 2 days I was feeling like well.After 2 weeks I felt well for 1 week but again from 2 days I am getting cough and cold(full blockage of nose) and before 2 days I had sex since then also cough n cold started again and also I am feeling very very weak.from 2 days in night I am taking Althrocin 500.Please help me,I am a student.I am feeling very weak.I had sex before too but I didn't feel this much weakness ever. Thanks