I'm feeling a bit concerned because I've been having this stubborn dry cough and chest pain that just won't go away. It's been sticking around since I caught a cold about four weeks ago. Sometimes it's not too bad, but other times it gets really severe. I saw an ENT who gave me some antibiotics and syrup to try for five days, but there's been no change. The doctor mentioned something about needing a blood test if things dont get better after this. What could be causing this? Should I be worried about needing further tests, or is this just a common thing after a cold?

yes do a blood test ,- complete blood count, CRP