As per the information available online, in order to be a Community Health officer one need to have a Diploma in Community Health with no less than 2 years of experience or having a BSc Nursing depending on the recruitment category. So with Diploma in Physiotherapy you can't become a Community Health Officer.

So yeah! You can become a Community health officer after BSc Nursing but you will be required to have atleast 2 years of experience. So after getting 2 years of experience, you can apply for different positions of Community Health Officer.

To know more about the career in Nursing visit the link below:

https://www.careers360.com/courses/b-sc-nursing

I hope this answer helps. All the very best for your future endeavors!