Hello SeanB.
Thanks for your post. I can understand your concerns as this happens to me regularly.
It is difficult to tell people when they should be concerned about something like this as we are all different in the way our systems work.
For years I did not have this sort of problem and then for no apparent reason the symptoms you describe started.
I tend to try not to worry about anything stoma related until I start getting pain and even then I'll leave it a day or so.
Taking things like milk of magnesia or laxatives is unlikely to give you a definitive answer to your question, as you describe having heavy output before the lack of output. It sounds as if you have simply emptied out and the system takes a while before it fills up again. My own problems have coincided with distinct signs that I have a 'lazy -gut' and a 'prolapsed stoma' also gives a clue to the system not working like it used to.
With all these things, I find it useful, for my own peace of mind, to occasionally share my concerns with a stoma nurse, to see what they have to say.
On my last trip to them she told me that she thought that my colon was just a heap of mush,. and it was not likely to ever work as well as it did at the beginning.
My take on this is that, at some time in the future, if I have worse problems, they are likely to recommend taking out or bypassing the offending colon and giving me an ileostomy to replace my colostomy. I have decided that for now I will continue with what I've got and take whatever comes.
I hope that your situation is just a temporary blip, or that you will settle down to the new 'routine' as if it is a new 'normal'.
I do hope you get some more replies to your post, as it is good know that others are in the same or similar positions.
Best wishes
Bill