Could Irregular Periods Be Due To Hardness Of Uterus?

Hi, Iam 40 years old, for the last six months my periods are irregular, my last periods was on jan 12th after that it has not come, this uneven started just six months back, recently when i went to a dr she had given one medicine for the periods but she checked and said you are having some hardness in the uterus you have to undergo one scanning, she checked and said, iam not pregnant. now iam mother of 2 child