Is there someone in your program who is supposed to help you negotiate your work at your clinicals? If so, I would talk to that person about your concerns. Or if there isn't, take it up with your adviser if you have one. Helping you negotiate these things is part of their job. Sadly you do need to disclose these things if you are going to ask for accommodations, and you have to disclose the need for accommodations before you need them. If you do it afterward they don't have to accommodate you for anything that happens before you ask for them. This wont be the first time that HR will have dealt with this issue. It wont be new to them. I hope everything works out.