The answer really is... it depends!
First and foremost you need to listen to your body. There are certain injuries that clearly require rest and a different kind of nourishment. However, if you are working with issues such as muscle sprains, sciatic pains or joint problems then a carefully approached yoga practice can aid in the healing process whilst ensuring you do not develop compensational patterns of tension.
Arrive a few minutes early to make some time to chat to the teacher before class about any issues you may have. All of our teachers are trained in modifying and adjusting to ensure the maximum benefits of the practice for a whole range of conditions.
You aren't required to disclose anything you feel uncomfortable disclosing, but what we don't know about, we can't help you with, nor can we be held responsible for problems that occur as a result of nondisclosure.