Your shared information does not make much sense without times/dates of the PSA tests in regards to the phases of the combo treatment, and in regards to the protocol of HT. Typically the combo starts with an antiandrogen plus agonist administered for a period of two to three months, before starting the radiation. HT then continues concomitant with the RT, followed by a adjuvant period that could last three years dependent on the chosen protocol. I believe that this was your case.
Nevertheless, some doctors (and patients) do HT with only an antiandrogen before and during RT (neoadjuvant + concomitant) which does not assure castration levels. The results are an increase of PSA due to inflammation of the gland which can last several months even if one continues with a similar adjuvant HT. In such condition some doctors prefer to administer, then, a different HT protocol as a precautionary approach (in case of high risk patients).
I do not know how far back was your RT done but the decrease in the PSA (22.2 to 3.2 ng/ml) could also be due to the effect of the previous RT added to the manoeuvrings of the hormonal manipulations.
In conclusion, I think that you can trust the result. However, if you still think that as a “glitch in the process”, you can repeat the test in a different trustful laboratory now or in one month time. You do not need to wait for the 3-month periodical.
Can you share more info on your PCa case?
Best wishes in your journey.