Distention and severe abdominal pain

On Saturday, I had my normal d. So, I swallowed an Imodium caplet that w Simethicone. Shortly after, I started to have flatulence and I thought that this was caused by the Simethicone. Yesterday, things became worse. I had severe cramps and tenesmus. I wanted to pass gas out but couldn't. I know this happens when I have rectal spasm. I slept w/o taking any medication. Woke up in the early morning w severe stabbing rectal pain. So, I applied the GTN cream (though it causes low blood pressure) and could finally pass gases. When it was time to go to work, I had severe abdominal cramps and I noticed that 2/3 of my abdomen was swollen or distended starting from the the left side. I was crying out of pain. So, I took a painkiller injection and my normal stomach and colon meds. I added an antispasmodic w peppermint to relieve the bloating. Still, there is pain. I'm curling in bed. These symptoms have been recurrent lately and the cause in unknown.