Spotting happens and especially when you describe yourself as irregular. brown blood is old blood. Women can get this from time to time. Spotting red and brown blood can also be a hormonal balance issue. Nothing serious but the same thing that causes spotting is what causes periods to be irregular so it's no surprise that you occasionally will have this spotting. I would not be scared or worried. However, at some point, you should talk to your doctor about being irregular and your hormones. They may do some blood work to see if they are out of whack and start birth control to regulate them. So, at your next well check doctors visit, talk about this with the doctor. good luck