I have a swelling at the crown of my head between my skull and scalp, when preasure is greatest my scalp itches and weeps. headaches and nausea ?

Possible infection: I recommend a visit to your doctor. You symptoms may indicate an infection that needs drainage and/or antibiotics. Alternatively, it could be a local skin irritation or condition (like psoriasis) which could benefit from medication.

May be dermatitis: The symptoms you talk looks like an ulceration and dermatitis. Mya use Hydrocortsone cream2% may relieve symptoms. Use the cream twice a day morning after shower and night at bed time