Tonsillectomy is a surgical procedure to remove tonsils that are cause problems such as:
- Frequent tonsil infections
- Snoring and obstructive sleep apnoea
- Abnormal growth or size which is suspicious of cancer
From the photo provided, there is a benign-looking cystic growth that is close to the area where the left tonsil used to lie in your throat.
This growth is likely a retention cyst or pyogenic granuloma (which may or may not be related to your previous tonsillectomy). Retention cysts are collection of trapped mucous/saliva that can occur anywhere in the mouth/throat region.
Pyogenic granuloma are benign scar-like tissue with some vascular channels. Both retention cysts and pyogentic granulomas commonly occur after some trauma in the mouth/throat region. They can be removed by a simple surgical excision if it causes symptoms such as discomfort, pain or bleeding. However, due to the location of your growth (which is at your throat region), the surgery will likely need to be performed under general anaesthesia.
I would suggest a visit to an ENT Specialist for an assessment to determine the likely cause of your growth. Hope this helps and all the best!