In my book, the question of medication in sobriety all comes down to a matter of intent.
If you take as directed a medication prescribed by a reputable physician with the intent to obtain relief from a condition that otherwise would impair your functionality or even imperil your survival, you’re still sober.
That goes for so-called "mind-altering" meds as well as others. The argument that someone isn’t "truly" sober unless completely free of mind-altering substances is based on the notion that all brains are created equal and will revert to a state of inherent perfection if unmedicated, which is patently not the case.
If you take prescribed drugs with the intent to get high or to escape reality, then no, you’re not sober.
I agree with the suggestion made by others that if you don’t trust your doctor 100%, or you feel he may over-prescribe, then seek out a second opinion.