I have a 60 year old Calamondin ornamental tree in a container. It has been inside since the fall. Did fine all winter. Several weeks ago it started dropping leaves. Now there are branches dying. I have not changed my watering habit, so not sure if I need to water more or less. I do not see signs of bugs. Any suggestions for care? Are there tree specialists that make house calls?

Are you in the southern hemisphere? It's very common for citrus trees to drop ALL leaves during fall/winter. They barely need any watering during this time; just enough to keep moist. They will push new leaves come spring.