Constipation in old people

I'm 80 years old. Five years ago I had radiation for postrate cancer since then I have severe constipation. The doctor gave me some medications but nothing works. When I go to the bathroom I cry from the pain. Is anybody that had the same problem after having radiation? Any help will be greatly appreciated.
Have you tried to treat your condition with constipation home treatments? If you are interested, here are some suggestions. Drink vegetables and fruit juice with pure water every day. You can blend cucumber, celery, carrot, pear, apple and avocado. It's a great constipation treatment and also great to keep you energized. It also cleanses the colon. You can drink warm water with lemon as often as you wish to. Helps build the colon walls and eases constipation. You can drink a mix of flax seeds powder and water in the morning before eating breakfast.

I know a lot of people takes lots of vegetables and fruit, but none work. I had the same problem.Recently, I had constipation and sometimes the tip of my stool is mixed with blood!So after advice from my mother, I started taking honey drink (honey mixed with warm water) every morning after I've wake up. It kind of soothes your stomach and lets you feel less bloated.Then in the late afternoon or evening, I will take about 8oz-10oz of prune juice. It works for my within 2 hours. The stool will be watery and passes out easily.Not forgetting, remember to take lots of water and especially orange juice throughout the day, so that your body feels less dehydrated and it will probably also ease constipation.Honey drink and prune juice does wonders!Hope that helps!