Hi, It can be due to upper respiratory tract infection like pharyngitis or laryngitis or sinusitis, may be acute bronchitis,pleurisy etc You can go for routine blood and X- ray chest with sputum ( if still coming) examination, it will be helpful to make clear diagnosis. You should take antibiotics ( quinolones or macrolides group) with analgesics and antiinflammatory, antihistamines in combination with mast cell stabilizers to combat dry cough. Don t worry about stomach ache and fatigue, it will subside with the infection. You need to see pulmonologist for further advise. Thanks.