What Causes Stomach Cramps, Itchy And Swollen Anus During Period?

I had severe stomach cramps 3 weeks ago, doctors found nothing through blood tests or ultrasound except my pancreas results were slightly up. They assumed it was a reaction to penicillan medication I had the week before. I have had itching around my anus and towards my vagina leading up to my period for the last few months but this month it has been continuous. My bottom appears slightly swollen, I find I itch it during the night and it's really itchy first thing in the morning. I am 35, about 167cm, 56kg and have great medical history except sinus, chest infection and occasional vaginal infection after antibiotics.