Welcome to the site.
I am sorry to learn about your condition and I empathize with you.
Well it seems like you have been suffering from what is clinically termed as Panic attacks which are also called as anxiety
attacks. These are nothing but episodes of excessive anxiety which develop suddenly and give the person a feel of dying or loosing control over self often accompanied with choking
sensation or chest tightness
and body parts or dizziness
Also like it happens in your case these anxiety episodes aka panic attacks spontaneously subside on their own in a few minutes.
Since your health check has come out to be normal so panic attacks at your young age seem to be the most plausible diagnosis taking into account the clinical picture that you have presented.
You shall discuss this diagnosis with your treating doctor and ask him to get you started on an anti anxiety drug combination of escitalopram at dose of 5-10 mg / day and clonazepam
at dose of 0.25-0.5 mg twice a day for period of at least 6-8 weeks, this shall take care of your underlying condition. It is qite possible that after starting on these 2 drugs your panic attacks get completely controlled within 3-4 weeks only but for preventing any possibility of relapse it is advisable to complete the full course.
Lastly I will like to reassure you that panic attacks although they may appear as potentially life threatening situations but in reality they are not that serious and are easily controlled with medications such as those as mentioned above , so kindly discuss this with your doctor and reach a decision on what can be done for your condition.
I hope this helps.
Wish you all the best and speedy recovery.