Do I need a Biopsy? Is it Colon Cancer?

[bran_sun]

Hello just to state im 23 years old. Anyways, I have posted on here before, however, I am more concerned than ever. I have been having some stomach issues, no blood seen or anything. I went to the Gastroenterologist he said I have IBS, and that I cant have anything serious given my age. I had some CT scans done and the found 3 4mm lung nodules the results are as followed:

Result:

The thyroid is unremarkable in appearance.

There is no mediastinal or hilar adenopathy. The heart is normal in size.

The chest wall is within normal limits. There is no axillary or
supraclavicular lymphadenopathy.

The airway is clear. There is a 4 mm nodule of the superior left lower
lobe on image 36 of series 3. There is a 4 mm nodule of the left lower
lobe on image 139 of series 3. There is a 4 mm nodule of the right lower
lobe on image 133 of series 3.

There are no suspicious bony findings.

I am so scared that this lung mets from colon cancer!!!! Please can someone give my any advice? My doctor is being very slow with getting back to me. Thanks.