I need to define a fhir resource for a Healthcare Protocol with multiple steps.

Suppose the Protocol is as follow :

1. Take observation of a patient for the first time. Based on the observation, prescribe a medicine, and schedule another appointment for one month later.
2. After one month, based on the observations, prescribe another medicine with the previous one, and an another appointment is scheduled for one month later.

This goes on for a couple of months.

I need a resource or a complete flow by which i can predefine the protocol, and suggest the steps to the practitioner, who will instruct patient accordingly.

I tried using PlanDefinition resource that contains multiple ActivityDefinition resource as actions. But then there will be multiple PlanDefinition resources for a single protocol.

I need something that can contain a complete protocol, and handle the logic part (i.e., take action based on observation value of the patient) as well.

Is their a way to achieve that usecase?