This sounds just like a herpes outbreak....But you will not know for sure until you get a blood test. You have to see a doctor for a blood test and you need to see doctor so they can prescribe medication to ease your pain and suffering. You need to tell your parents. IF it is herpes the sores will clear on their own in 5-7 days and then virtually disappear. But more will come and it will be just as bad. Also once they go away and you are clear you can still pass it on to others. You really should get tested. If you are positive then you can give people herpes and not even mean too.
I understand that your parents will be angry but its time to fess up. They are the only ones that can help you right now. I have herpes and I understand how hard it is going to be to tell your parents, I had to do it. But no matter how much you dont want to do it, it still has to be done.
There are some ways to ease the pain from home.
1. Take a warm bath with 1 cup of baking soda. Only fill the tube to about 12 inches. Soak as long as you need to. This will clean the sores along with soothe them.
2. You can buy abreva at your local grocery store. This is for cold sores on your mouth but they work really good on your sores down there.
3. Wear lose cloths and no undies if you can. Wear skirts if you can.
Other than that there isnt a whole lot you can do, you just got to wait until they pass. But if you have herpes there is medication out there that will help you not have any outbreaks.....Best Wishes