What Causes Brown Vaginal Discharge While On Microgynon Pills?

Hi, (sorry if this is too graphic) Im currently on the contraceptive pill microgynon 30ED, the one where you take 21 consecutive pills, then 7 sugar pills. This is my third month on the pill. As expected, during the 1st month my period was irregular and i experienced headaches and the overall feeling of being ill, most likely due to my body getting used to the pill. By the second month my period was regular and there was no sign of any of the previous side effects. I came on my period 2 days after starting the sugar pills and came off the day i finished taking them. I always take my pill from 12.00-12.20 depending on when i have my lunch but mostly at 12.00 and i have never missed a pill. This month is my third month taking the pill. This month I came on my period during the second week of my contraceptive pills. I thought this was strange although googled it and figured it was just breakthrough bleeding. For the first day or two of the third week (this week) i thought my period had finished but it hadn t. I now have very light bleeding and brown mushy vaginal discharge which really doesn t show up on tampons, but does show up if my boyfriend fingers me or we have sex (on his fingers and penis). It doesn t have any particular smell but since I ve started having this discharge my vagina has been a little itchy although i don t know whether this is because of irritation or actual itching. I thought it may have been a cut as when i peed once my pee touched the bottom of my vaginal opening and it stung. The bottom of my vaginal opening really hurts especially when my boyfriend puts his penis inside of me at first. After we start having sex however and as long as he doesn t take his penis fully out of me and go back inside of me it doesn t actually hurt. I put aloe vera gel on and inside my vagina which seemed to make it less uncomfortable but it is still very uncomfortable and I ve been on this period for 2 weeks now. Ive been feeling really stressed and hormonal to, I ve found since this has been happening I m very emotional and seem to get upset and angry much easier than usual. Im not sure whats wrong with me, I took a pregnancy test at the start of this week to rule out pregnancy and the test came back negative, but when i researched it said the mushy discharge may be due to miscarridge? I m mainly concerned about the brown mushy discharge and the fact that my vagina isn t comfortable, and was just wondering if you could suggest anything thats wrong with me and what i could do about it. I would be grateful for any help. Thank you for your time, my apologies if this was very long.