how after my b.pharm I am became a doctor
See if you are thinking of clinical Physician kind of a doctor then after B.Pharm you won't be able to do so. For that you have to do MBBS or BDS or BHMS.
Now if you do a phD after doing M.Pharm then you can use the prefix Dr. in your name but that will not mean that you will be given a medical licence as a medical practitioner.
I hope you got my point. All the very best for your future endeavors!