Absolutely safe. I'm a physio, and while it is very important that the physio treating you knows you are pregnant, there are many, many techniques that s/he can choose from to treat your problems.

Your first ob may have scoffed at the term 'out of alignment', as this gets overused and misused by some health professionals and by the public. It would be a rare ob who would scoff at the idea of physio being useful for a musculoskeletal condition.,