Your question attracted me to this unfamiliar territory
I want to troubleshoot this problem for you
It's not uncommon for people to experience the same level of discomfort whilst driving a car long distances. This uncomfortability arises from the torso and lower body converging from 180 degrees (standing) to 90 degrees (seated) and remaining fixed for extended periods of time. Now, as a consequence, compression results in the abdominal region. This causes the stomach muscles to flex outwardly. If this area is layered with excessive subcutaneous fat, the outward protrusion of the stomach is exacerbated, it propagates further. Essentially, you are increasing the volume of matter into an area incapable of accommodating the protuberance, i.e. size 36 pants (amber caution).
If left unresolved, because abdominal organs are fitted with various pain receptors that detect abnormal mechanical and chemical stimuli, they send signals to the brain which leads to the sensation of pain or feeling bloated, etc. The mechanisms to produce the “bloating belly problem” would be:
Inflammation: This leads to the production of special chemicals that activate the pain receptors.
Ischaemia (lack of blood supply).
Stretching of muscles and the capsules (coverings) of organs.
Nerve stimulation: Sometimes tumours can invade nerves and cause pain signals (master caution).
To resolve the discomfort would be divergence of the lower and upper body (stand up). But you can’t do that. So what do you do? What you did, wear size 38 waist pants (>36), but with an elasticised waist. You can either buy them of the shelf or have yours tailored. They exist and work as advertised.
Alternative long term solution would be healthy eating and exercise (my choice). Will reduce not only subcutaneous fat, but reduce the stubborn visceral fat.
Of course, seek professional medical advice from your physician if the irritability persists.