tickling in bronchia and headaches for 6 weeks

[meTine]

I've been sick for 6 weeks and don't know what to do anymore. I have a tickling in the mid chest area which causes me to cough dryly. Additional headaches and slight pressure on my sinuses. In the beginning I was very very fatigue with it, was in bed for almost 3 weeks. I had texted with my physician and after being sick for 11 days, he had put me on mild Antibiotics Azithromycin 250mg for 5 days (first day 500mg) saying I probably have walking pneumonia. I had Mycoplasma walking pneumonia 2x before in 2009 already.  It slowly improved after taking it and I'm better, but still not healthy and feel it is getting worse again. Every inbreath I feel a cold tickling in the mid chest area and feel I need to suppress a dry cough. I have no postnasal drip, just a slight pressure on my sinuses and headaches and still feel fatigue and tired all the time.
I've been to Costa Rica in August and came back with a nose cold for 1 week, after that was healthy for a couple of days before all these symptoms started. Can it have anything to do with that trip?
What should I do? What kind of doctor or diagnostic and treatment would help me?
I would appreciate any help please!

Thank you very much,
    Tine