With health anxiety self diagnosis is a very very bad idea. It feeds the anxiety exponentially. I see it like scratching an insect bite - momentarily you feel more in control but then the poison inflames and the scratching urge is even greater. I say this as a completely non medical person but wife of a sufferer crippled for several decades by health anxiety which with lots of support now over the last decade has become more manageable identifiable anxieties.
When did you last seek medical support for something?
If it's within the last three years, and this pain has been going on for that long, ask yourself why at that stage you chose not to mention it?
Now think to yourself how many things you've incorrectly self diagnosed. When did it help - If ever?
On a scale of 1-10 assess how urgently you need medical support, you can repeat this daily and record it to see if you have anxiety pain patterns.
Ask yourself, will this wait a week for a nonemergency gp appointment, then after a week, will it wait a month so you can discuss any other issues that occur?
Would it be worth a non emergency appointment to seek CBT or similar to start in the path of managing the real route of mental pain manifesting itself physically. Drugs can be very effective and with so many types and doses available to manage either immediate panics or longer term anxiety levels they may be a good option to make life better for you.
Each day can you see if you can work on managing the anxiety by getting at least 30 minutes out in the fresh air, ideally walking or jogging letting your mind wonder and take in the surroundings at your own pace. This air exercise combination comes up so often in treatment plans from different places and there is something very effective in it.