What can I do my 7 month old has a cough and fever?

Fluids/monitor. Your 7mo is due for 5-7 uri's/yr to age 5 & most can be monitored at home. Playful times/fluid intake enough to wet diapers every 6hr/breathing not too noticable all suggest home care ok. Lack of play/noticable incresaed work to breathe/poor fluid intake all suggest a dr visit in order. Nasal saline helps keep the nose clear & tylenol (acetaminophen) as a comfort med may help.
How high a fever? Most likely a cough and low-grade fever lasting a few days is just a "cold", a viral upper respiratory infection. Fever over 102 f (39 c) should be evaluated by your child's pediatrician as bronchiolitis and pneumonia are possibilities.