I have been on the birth control pill for 15 years. This past month I had spotting and cramping, plus back pain, in the middle of my cycle. Could I be pregnant? What's causing this?
There could be any number of reasons unrelated to pregnancy or birth control pills. Our bodies do change. You can try to rule out pregnancy if your normal period is more than a week late, or even markedly changed from normal, by taking a home pregnancy test, or being tested by a doctor.
If you haven't had a pelvic exam for some time it might be a good idea to have everything done at once. You can read this article by Merely Me, a writer and community leader here, about, Bleeding Between Periods: What Does It Mean? It may give you some information about the changes in discharge and the cramping. There are a number of possible causes and most will require a doctor's examination to find.
Here is more information about the types of discharges.
And here are some other links you might find useful:
6 Tips for Dating Your Spouse
Bumps on the Vagina: How to Know If It’s Serious
5 Gynecological Symptoms You Should Not Ignore