3 week cough

[My boy]

Hi my 5 year old has had a cough for 3 weeks worse at night. Blood sugars rising sometimes ketones sometimes not. Been giving sugar free calpol which isn't helping!! Should i take him to doctors. Just the last time he had a cough they gave me nothing for it. They probably think oh god heres this paranoid mother coming again. Any advice would be helpful. Thanks in advance Loreen.