Weirdness after period

So this has been happening to me for a couple of months now but when I'm off my period I would start having a lot of dark brown gooey discharge and I feel like it only gets worst every month. It's so much discharge as if I have so much old blood stored up there 😣But now I've been seeing some new blood so I'm very concerned. I wonder if going on birth control can help??? Please comment and help!