Is it normal for my period to be messed up after pregnancy and breast feeding?

My periods are usually pretty regular. I had a baby 1 year ago, and stopped breast feeding 3 months ago. I have been back on birth control pills for 9 months now. My normal period came back about 5 months after giving birth. For the past 2 months, I will get what I think is the start of my period, but it's just pink and brown blood that clears up after a day. About a week or two ago, I woke up with the most horribly painful cramps I have ever felt in my life! I didn't even want to move. I went to the bathroom and noticed I was bleeding like a regular period. Within 10-12 hours, the bleeding stopped completely. I have had sex with my husband every night for the past 3 nights, with no issues, but when I woke up this morning, I noticed a pink and brown discharge on the toilet paper after using the bathroom. I thought I might be starting my period, so I used a tampon. When I changed it about 4 hours later, it was about half covered with only brown blood. 3 hours after this, I took it out and it was pretty much clean. I used a thin panty liner just in case, but I have not bled at all now. I don't know what's going on and I don't have insurance to see a doc right now. Any idea what could be going on? Is my body still screwed up from the pregnancy and breast feeding? Is this normal?