My OH had his 5th Prostap3 injection last month, always alternating between arms, though the 4th one left his muscle constantly aching, and it has never eased off. Don't know if that's a sign that it was administered incorrectly or not, as the other 4 didn't bother him. He now has a month to decide whether or not to have the next one in the sore arm and risk making it worse, have it in the same arm as last time, or ask to have it somewhere else.
Elle x