what should I do?

I would definitely go the interview(s) at the hospital and see what they have for openings etc. Do you have a sense where you would rather work? It would be much better to go back on your agreement about working at the nursing home before they actually put any money into your orientation. (obviously) So, I would either just tell them straight out that you have possible other job opportunities or ask if you can postpone your orientation for a couple of weeks and not give them specifics. Good luck, I suspect that whatever happens you will make it work out!