Why am I bleeding whilst on birth control?

I'm in my second pack of Necon 1/35. I skipped the last week on inactive pills of the first pack and went directly into the second. During the time I was supposed to be on the inactives, I started spotting. While starting the second pack, I continued to bleed the entire pack through. I am almost done with my second pack and will be getting the third on the 14th. The spotting is light, brown but sometimes a deep red. Some days it's not there at all. If this has any significance to my issue, my boyfriend and I have sex very often and when we get into it... the bleeding stops and starts back up again when we are done or sometimes quits for a few hours. Do I need to actually take the inactives this pack and get a thorough bleeding for it to actually stop?