Hi I'm Going To Be 53 Next Week. I Haven't

Hi I'm going to be 53 next week. I haven't had a period in 4-6 months and today out of the blue, I had a heavy discharge of thick clear fluid with spots of blood followed by more clear fluid with light blood stain and lower back cramping especially on my right side but not terrible pain. Just a little discomfort. I am physically fit for my age. I work out regularly and I'm not overweight. I'm not sure what has caused this. It could be just a period but not like my regular periods used to be. There seems to be a fair amount of clear fluid coming out as well with a few drops of blood in it.