This is a common complaint from women after having breast augmentation by silicone implants.

First of all let’s agree on what test you should do when you have any symptoms;
if you are under the age of 30, a breast ultrasound is advised.
If you are over 30 then please do a mammogram and breast ultrasound.
If the results are not conclusive, your doctor may ask to do an MRI of the breast.

The cause of your lump may be just a bulge from the implant, focal dense glandular tissue, a cyst (fluid lump), a benign solid lump (a fibroadenoma) and the last diagnosis may be a cancerous tumor.

Silicone implants do not cause cancer, but they are associated with breast implant associated Lymphoma (BIA-ALCL).
This can happen in 1 out of 2969 women with implants. Its risk increases with textured implants.
It is a cancer of the immune system not breast cancer.

The FDA recommends periodic imaging, typically an ultrasound or MRI, for silicone gel-filled breast implants starting 5–6 years after initial placement and then every 2–3 years thereafter, even without symptoms.
This routine screening helps identify silent ruptures and monitor overall breast health.