Just because you may currently have HPV does not mean you will always have it. Some people clear the virus without ever knowing they have it and the HPV not causing any health problems. Just because someone has HPV does not mean they will go on to develop oral cancer. I hope you do not have any serious health problems going on!

Since I have no idea about how the health system works in your country I dont know how much help I can be. You need to find an ENT who is familiar with oral cancer patients. Not one who's main job is to put tubes in childrens ears. Since you said your ENT is not familiar with the HPV and oral cancer link then obviously they are behind the times in their medical practice.

Find a more up to date ENT who treats mostly oral cancer patients. By finding a qualified ENT they will look for a tumor and do a biopsy, probably scope you to look deeper into your throat and if something is found then further tests like a CT. I would doubt they would do a PET scan unless cancer was found. They could put you on some medications to try to alleviate the symptoms, as it could be other things besides oral cancer.

The swollen lymph node could be a sign of infection. Please stop worrying so much! It does not help you at all and will only make you feel alot of stress which isnt healthy. At this point you dont even know if anything serious is wrong and worrying will not change that. Do yourself a huge favor and think positive, stay busy and go on living your life. If you must think about the "what if's" then limit yourself to say 5 minutes then "change the channel" and think of more positive thoughts. This is something you can learn to help you have less anxiety about your situation.

Good luck with everything!