I'd tell them because if it's a new thing you've not been treated for prior, they're going to be more focused on finding out why it's started in hopes of stopping it that way instead of knowing the why and trying to find a way to fix it despite that change, because that change is here to stay I'd assume so the challenge is in their hands. Many things can start acne problems, but in your case the most likely reason is T and since this is a new thing for you that wouldn't be new to the vast majority of males, it's worth mentioning. Cut out the middle man and get to the solution in spite of the cause instead of them wasting time and suggesting things to try in trying to find the cause so as to erradicate it. You can just say you take T, they won't need to know more so you can get away with saying it's for hypogonadism, that's exactly how mine is recorded in my medical notes. They won't need to know your dose. Taking T only equates you with other males so it won't interfere with meds unless it increases risk in major risk factors like heart, BP or blood. Even if pushed into saying dose you still don't have to out yourself. I saw a video recently with a cis-male who had hypogonadism and a lower T level than I had pre T at only 0.7-0.8!