Hi Malu. I hope by now you have found an answer to your question. If you havent seen a doctor and your vulva itches and is sore then you probably have Thrush, which can easily be cured .You should be able to buy Canesten pessary and cream at any chemist/pharmacy. if you are sexually active then your partner should use the cream on his penis as well.
Do you have any symptoms or does it itch or hurt? Are you sexually active? Honestly from the picture it just looks like vaginal discharge/mucus and particles from toilet paper. You can have clumps of discharge and vaginal mucus especially when you’re ovulating. But it could also be something more serious like an STI which is totally treatable! If you’re experiencing pain or discomfort make a visit to your PCP, OB/GYN, or CNP.