It’s been well covered already, but this is what I’d recommend
Head to toe assessment. I’d want to know if his cough is productive. If so-color, amount, and frequency. I’d want to know his last drink, if he was using drugs-when was the last drugs taken?
What labs do you want? CBC, CRP, CMP, HIV, LFTs
What other diagnostic tests should we run? Chest X-ray. Possibly chest ct