If you want to get it properly investigated you can always confide in your doctor and he is a best guide.Sometimes infectious swellings goes away with simple antibiotics so this is logical step.If it persists you can go for further investigations.If you are not satisfied with your doctor you are always free to go for 2nd or even 3rd opinion also.On this platform you are getting multiple opinion online, but it is not a substitute for direct examination and offline consultation.
Next Steps
If your doctor decide FNAC ,USG ,CECT , Biopsy ,blood tests are there to investigate swellings.
Health Tips
go as per your doctors advice offline.