Hi ,
There could be many causes of hairloss and especially Bald patches . Bald patches need more evaluation like if there us any raised lesion/white patches that will likely be Psoriasis. but if simple bald patches it could be due to stress, hormonal changes especially post menupause .
I will recommend going to Dermatologist because it needs to be assessed further.
but simple measures like diet rich in zinc , biotin, iron helps to prevent hair fall .