Passing stool. For your response.

Hello, Hope you are doing fine Its been a year I am unable to pass stool. Sometimes I am able to but it's only when I take medicine. But these medications work sometimes and not always. I am not facing any problem with urine passing, my only problem is with stool passing. I take 4 meals a day and in between these meals I usually eat snacks. So it's not that I am not eating properly I eat a lot but still i am facing this problem. Also the quantity of food consumption is not shown in my body. I am thin and I weigh 45 kgs. My age is 31 years. There is no sign of fat in my belly or swelling. It would be helpful if you could suggest me any test or symptoms of any kind of problem I might have. Looking forward for your response. Thanks and Kind Regards Saba Khan