I have a similar story (not sexually active, age is 48 and a half). I recently saw my OB/GYN and had a blood test on my hormones. Yep, I'm menopausal.
Also, a dark red versus a bright red does suggest older menstrual flow. It's inconvenient that this is taking so long for you. Ask your doctor if two tablets of 200mg Ibuprofen would be okay for you to take, and if twice a day or three times a day would be suggested. (Having a nurse tell me to try this made a surprising stop to a long ongoing period I was having!)
I hate to answer your question with a question but isn't more iron in your diet worse when a lady's hormones are menopausal? This is definitely something to ask your doctor. (For instance, one of the differences between Centrum and Centrum Silver is that Centrum Silver has less iron.)
Good luck and hang in there!
D.