Hi..
Can understand your concern..
As per your complain painful knot under the chin can be due to infection in the sublingual
salivary gland present below the chin..
Sublingual salivary gland is one of the major salivary gland present below the chin and infection in the gland can lead to inflammation and formation of pus inside the gland and leading to swelling..
It leads to pain,swelling and at times can cause rise in temperature of the body too.
The infection can occur as there are more chances of food debris and bacteria to settle in the floor of mouth and the infection can travel from the ducts to the gland.
Another common cause seems to be inflamed and swollen submental
lymph nodes that can occur due to infection in oropharyngeal [head and neck] regions..
I would suggest you to consult an oral pathologist and get evaluated and investigations like
x ray,
MRI SCAN etc can be advised for ruling the exact cause of the swelling and pain and treated accordingly..
In case of infection antibiotic treatment like
augmentin or clidamycin etc along with anti-inflammatory pain killer like
ibuprofen can be relieving..
If it is a lymph node along with medication do alternate warm and cool compresses..
Hope this information helps.
Thanks and regards..
Dr.Honey Nandwani Arora.