I kept an eye on their watering and used on of those water meters as well. Just wondering if it's the soil-based compost that was a bit too cold and wet down below.

It's worth a try on both.

 My usual sea bass and a few chips and peas lastnight , pineapple and ice cream 
  out for supper tonight 

Mrs. B, I will also say good on you for following through and getting a thorough diagnosis. Also glad for you that the doctors think the lump is not malignant.

As you have said, men also need to pay attention, and get yearly physical exams! Including a prostate-specific antigen (PSA) test.

I'm living proof.  A routine physical last September showed an elevated PSA.  That led to a repeat PSA test, with a higher result. Then a urologist appointment, exam, and another PSA test (higher again) and conclusion from the urologist that prostate cancer was likely. Following that, an MRI in February which found a lesion, with the determination that cancer was even more likely, a biopsy is needed. Finally, in mid March, a biopsy. Diagnosis? A benign condition, but one that could lead to cancer. Bullet dodged, but the PSA test frequency will increase from annual to twice a year.  I was very lucky (at least for now).

Listen to the lady, gents!  Mrs. B's advice is as good for the gander as it is for the goose!

Any photos?

My thoughts are: Have you been feeding them?  Are all the leaves yellow and have they changed at the same time or just the ones at the base? When were they last potted on? Was potting on into a new batch of compost?

If they are standard varieties might be worth getting some from a garden centre as a back up.