Hi ! Any kind of anxiety/stress
could give rise to such physical symptoms and signs. However, before concluding that the findings are due solely to stress, you should properly get yourself clinically examined by your family physician, who apart from measuring your blood pressure, may advise for an ultrasound/CT scan
if he also feels the pulsation in your stomach as described by you. If the ultrasound comes out to be positive for some intra abdominal pulsating pathology, then he may refer you to a higher center.
If after excluding all organic disorders in abdomen where such pulsations can occur, symptoms persists, then I would advise you to get some counselling
by a specialist Psychiatrist
In the mean while, you must continue your working out routinely once declared fit by your treating doctor.