Thanks to MN I have finally realised that the most likely reason for intermittent but pretty constant pain on my sides, followed sometimes by excruciating pain, and intermittent spotting, is likely to be cysts dealing with themselves.
Having been brought up by a DM who discounted any pain but hers, I have ignored them for years.
Should I do anything? Having Googled it seems to say that they mostly sort themselves out. I don't want to take up unnecessary time or worry about something perfectly ordinary.