Welcome to HCM.
You could wrap wide cloth around your abdomen fairly tightly. Do regular tummy reducing exercises, such as raising both legs in the air without bending your knees, while lying down supine in the bed, try tucking your tummy inwards and holding it in, as long as you can, whenever you get the chance to do that.
See that you have regular bowel movements
, by drinking lots of water and adding lots of fibre containing items in your food and eating fruits.