A spot on chest x ray
is not so specific in itself unles you let us know the exact report details.
Coming to your precise question, the spot can be due to a number of causes including the pneumonia
that you had last September. A spot need not necessarily disappear if it is a residual shange in lungs. However I would recommend you the services of a pulmonologist who could surely guide you to further imaging investigation if required. At the same time a pulmonogist could also certify that you are not suffering from any communicable disease if that applies to the visa requirements.
Wish you a pleasant trip soon.