If you are living in a hot and humid climate check
for mold in your house and work environment. Often
mold spores are the culprit.
Yes, moving to a Mediterranean island may help if the allergens are not found in that area. If you benefit by going there for a month, then definitely there is something in your area that’s not suiting you—pollen, spores, animal dander etc are common causes.
Consult an allergy specialist. Take care!