A few thoughts...
- Dehydration is a common trigger, and it's easy for that to happen if you work out for long periods.
- Milk of magnesia is your friend. It works by changing the osmotic balance of your intestines and keeping more water in the intestinal tract, making things softer. Great when you are having issues.
- I cycled regularly with hemmorhoids and not many issues. I think it would be harder to keep them reduced with running because of the impact. If cycling is an option, I recommend it. I did it even with 3rd grade ones. Exercise is good at getting the blood flowing and that helps. If you can't run or cycle, walking is pretty good as well.
- Banding is mostly painless if done right and has a pretty good track record. I don't think they work well with 3rd grade, but if they reduce back to 2nd you are a good candidate. You can help this along with direct pressure and trying to (gently) push them back inside.
- If you have access to a hot tub, that really helps.