I may have missed something here, but I just totalled up all the credits I have with all my projects (both active and retired) and that total comes to some 14 million more than is shown as my actual total. A quick look down the list shows the main culprit is probably GoofyxGrid@home NCI as it has an almost identical number against it. I say almost identical as it's a moving target as I'm currently working on it.
https://boincstats.com/stats/-1/user/detail/2304340/projectList
There was an issue a while back with GoofyxGrid NCI where they suddenly gave me a whole bunch of credits that I hadn't earned, and I contacted them and asked that it be put back to what it had been as I hadn't earned those credits and they did. However when this happened again I thought "What's the point? It'll just happen again" so I left it. Perhaps there has been some attempt to manually reduce the credits by BAM that I missed. If that has happened then that of course wouldn't take into account that I had already had my numbers sorted. I don't know if all this makes sense, I'm just trying to give as much info as possible. Hopefully I haven't just jumped to the completely wrong conclusion.
Thanks for your time.

OK So am I the only person with a total that doesn't add up? ... Nobody?

Willy remove the project stats when the credits went rogue back in August.

See ... GoofyxGrid@home a disaster

Thanks for that Dr Who Fan. I had taken a break from GoofyxGrid after I had complained to him and asked him to remove credit I hadn't earned, which he did, but that was before this happened so it passed me by. Looks like it's time for another break!