It sounds like it could all be down to IBS and anxiety (and the anxiety causing IBS) to me Phil.
Just reading back this thread for months...you are getting more upset and anxious about it, and then it seems the symptoms become worse.
Do you eat enough fiber? Not doing that can lead to constipation (it sounds like you've been getting that) which can then lead I think to alternating periods of being bunged up and then wanting to go all the time.
You can get natural laxatives from the chemists/supermarket. Prune juice and whatnot.
Good luck