hello and welcome to health care magic. I am sorry that you felt unwell.
Shortness of breath
and chest pain
on activity or at rest can be as a result of a number of different conditions. It may be related to something as simple as the level of personal fitness or it may indicate something more serious.
Some of the more serious conditions that can cause the symptoms that you are describing include: low blood count or anemia
( a person with anemia which means a reduction in red cell mass may have shortness of breath or chest discomfort
on activity because the reduction in red cell mass would cause insufficient oxygenation of the tissues )
Heart disease- if the heart is not working properly either because the blood vessels in it are blocked or the rhymth is abnormal, the structure is abnormal or contraction is impaired then chest pain, shortness of breath may occur. The person may also experience irregular beating of the heart, excess sweating or swelling of lower limbs
Any issues related to the lungs may also result in the symptoms described- infection whether viral or bacterial, trauma , inflammation of the lungs or ribs.
The stomach pain and headache may in some cases accompany the illnesses either as a part of the whole condition or as a stressor response. They may also be related to an entirely different condition altogether.
I would you advise to seek medical attention. Your doctor will ask you to specifically describe the nature the discomfort- the exact position, the time frame, what type of pain, what made it worse and what relieved it, accompanying symptoms. He/ she will review your medical, dietary history and will likely check your pulse, blood pressure, heart size and check for any added heart or lung sounds. He/she would then perform any investigations based on the findings.
I hope this answers your question and that you are able to find some definitive answers.