Hi mam...     your history seems it may be  a simple ulcer....After the white patch which cover over the ulcer gone , you may see that pin point bleeding as brown spots.....or it may some other condition like oral lichenplanus,leukoplakia which may be due to stress or some other habits... but without any clinical examination it is difficult to rule out your condition

Consult to dentist near by your area.

You can get a check up done from a dentist. May not be of any significance but it is good to get a regular check up done anyway