Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain if after getting a molar extraction done long back you still have nasty taste in mouth and also bad smell then it can be due to infection in the extraction site that can be probably due to any left over root piece in the socket..
Secondly it can also be due to any other tooth that is decayed or can be due to
gum infection..
So for this consult an Oral Physician and get evaluated and appropriate x-rays can be advised for ruling out the cause and will be treated accordingly..
As far as headache and bulging vein on forehead is concerned, it is not due to
tooth infection, and is not related to dental issues..
Therefore for this consult a Medicine Specialist and get evaluated and after proper evaluation and investigations like
CT SCAN, MRI ,
blood test as per suspected cause treatment can be done..
As of now take anti-inflammatory painkillers like
Ibuprofen for pain relief..
You can also start doing antiseptic mouthwash gargles..
Do warm saline gargles..
Hope this helps..
Regards..