It sounds like an infection of some sorts. Do you have a fishy smell? If so it can be a bacterial infection like BV which should be treated with antibiotics. An UTI can also cause some of these symptoms. Finally it can still be a low level yeast infection.
The irritation can also cause you to be horny as your vagina will interpret the throbbing and irritation as aroual.
Speak to your mom or see your doctor or nurse to find out what it is and have it treated.
Masturbation does not have anything to do with it unless you scratchesd or caused chafing yourself.