I am 53 years old, I have a prolactinoma for 8 year and took dostinex (cabergoline). 5 mg, the last year I have a very irregular period & this lasts me since dec 31?

Prolactinoma. You may be going through menopause. The high prolactin of a prolactinoma will certainly disrupt your periods, but if the Dostinex (cabergoline) is controlling your blood prolactin level, then your periods should return to normal.