Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain it seems that you have got an inflammation in the area under the tongue leading to appearance of swollen and inflamed vein and the most common cause of it seems to be traumatic ulcer that might have caused due to traumatic
injury to the underside of tongue that is caused with some hard foods or concentrated chemical liquids like mouthwash or can be due to burning with hot food..
Nothing to worry as it does not seems to be serious.
I would suggest you to take anti-inflammatory painkiller like
Ibuprofen..
Apply numbing gel containing Lignocaine or Choline Salicylate..
You can also suck ice pops and do cool water rinses..
You can take soft food and avoid spicy and hard foods..
Do warm saline gargles..
In case of no improvement consult an Oral Physician and get evaluated..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora.