I have concern for this 3 tables:

Appointment
-AppointmentID
-PatientID
-DoctorID
-AppointmentDate

Treatment
-TreatmentID
-PatientID
-DoctorID
-Treatment
-TreatmentDate
-Fees

Visits
-VisitID
-DoctorID
-PatientID
-VisitDate

The doctor can have 1 or more appointment. A patient can have 1 or more appointment. So the doctor and patient is associated through the appointment.

The doctor can provide 1 or more treatment. Each patient receives 1 or more treatment. So the doctor and patient is associated through the treatment.

The patient can go for 1 or more visits. A doctor can have 1 or more visits. The patient and doctor is associated through the visit.

Therefore how can visits and appointment be associated with treatment?.

I carefully relook at my diagram and now I understand
However is it advisable to have a status attribute inside the visit class?
status: Arrived, Visited, Left