Thanks for writing to us.
Feeling of knot under the jaw can be due to spread of infection from infected tooth into Peri apical area.
I would advice you to get a thorough clinical evaluation.
Usually in such cases,Amoxycillin
along with analgesics has to be administered.
Infected tooth has to be restored or extracted depending on severity of infection.
Heart beat felt in ears can be due to exhaustion,heavy exercises.
Maintain your physical health,be calm .
Hope this helps.