I Am Male 58 Y/O. 220 Lb. 5'11" Otherwise Healthy.

I am male 58 Y/O. 220 lb. 5'11" otherwise healthy. Within the recent 6 months i have noticed my trousers fitting more snugly. In the last 45-60 days I first noticed hard stool. I started trying metamicil which helped temporarily. Then I tried prunes which helped with the hard stool. Since then in the last 30 days, I have had excessive gas and bloating in my upper abdomen and my belly has swelled to where I cannot get into my Trousers that I wore before I lost 20-25 lbs one year ago... also I have a fullness in my upper abdomen and often in my lower bowel and feel I need to defecate, but strain as I will I cannot go unless I use a stool softener then it is a small amount, solid but only about the size of my thumb and in small amounts... afterward i feel better and my belching dissipates some but I still have a feeling of fullness in my lower bowel and my upper abdomen and the belching returns... it is almost like the fact that I cannot defecate causes a fullness throughout my digestive system, I still have a good appetite and I have no pain unless I take a laxative and then just some slight cramping as I defecate. My abdomen and belly are bloated like I have gained 25-30 lbs. I do not have a scale, but I do not feel as if I have gained weight, my belly just looks like it.