Hello and hope you are doing well.
Lung nodules can occur due to local causes like recurrent lung infections and sometimes due to cancer of the lungs. They can also be seen in systemic diseases like systemic lupus erythematosus, rheumatoid arthritis, sarcoidosis and scleroderma. Further evaluation will be based on whether the nodule is changing in size and systemic symptoms. A CT is indicated. A PET scan and biopsy may further help in evaluation.
Hope this helped and do keep us posted.
The nodules can have many causes, not all of them serious. but you have every right to be concerned because your GP was. By all means visit a pulmonologist and bring your x-ray with you.