@jime51
Hi,
In India, some ROs prescribe multiple supplements, including probiotic. Two other supplements prescribed to my father were Nancumin and Aktocyte ( https://dae.gov.in/launch-of-nutraceutical-aktocyte-by-the-department-of-atomic-energy-set-to-transform-cancer-care/ ); the prior is fairly common tablet with nano curcumin, while the latter is a specific supplement developed by the Department of Atomic Energy of India along with a lab, for reducing the side effects caused due to radiation.
Possibly your GI or RO won't be aware, but just thought of letting you know in case you manage to find the compound in some other supplements.
Also, for your BMs, if you are still taking probiotic or on a heavy fibre diet, I assume this is expected; probably reconsider diet? I hope you get right directions for complete healing.