Hi Leila,
I had something similar on Prostrap, I started on it and my PSA initially fell to 0.2, then 3 months later was back up to 3.5, then it fell away again to 0.1 and stayed on <0.1 for the next couple of years.
My local hospital has specialist Urology/Oncology nurses, who are readily available on the end of a phone without the need for appointments etc. They were very supportive and launched a bit of a 'Steward's Enquiry' into what had occured.
The consensus was that I might have been given a 1 month prostrap injection instead of a 3 month shot. The thing is that the boxes the Prostrap comes in look very similar and it's an easy mistake to make. My GP's surgery denied that they had made such a mistake, but then they would say that wouldn't they?
At my GP's surgery I have to collect the Prostrap from the pharmacy and take it with me to the nurses appointment. So subsequently I always made sure it said 3 months on the box.
Of course in a perfect world we shouldn't have to do that, but its worth yor OH keeping his eye out and reading the box, if for nothing else than his own peace of mind.
:)
Dave