Could kindly post my question anonymously

Could kindly post my question anonymously
I previously had a job in the UK for a period of 7 months before returning to my country. during this time i had a clinical supervisor who was also the head of the department that was very tough in nature but he agreed for me to add him as a reference for upcoming jobs at the time.
I recently started applying for jobs hoping to return soon but Im having extreme difficulties in obtaining a reference from him. I tried calling him and his secretary and sending him texts as well with no response. I believe that he does not even remember me because i got an email once from the secretary saying that he can not give the reference.
I am very distressed as this problem is affecting my job opportunities and I do have other registrar level doctors as references but I dont think that they will be effective since it clearly says on most application forms that it must be a previous employer or a consultant.
has anyone been in a similar situation? how do you think I should tackle this