There are two problems here to deal with. Vaginal itching indicates a skin irritation from the continuous moisture in the area, irritation from being in contact with a surface like sanitary pads and underwear, shaving, or the proliferation of bacteria near the vagina. There is also the possibility of disease but since you have not mentioned any odd discharge, you should be fine in this regard. Hemorrhoids are a problem caused by repeated spells of constipation that has caused the hemorrhoid tissue to be ejected out of the rectum, dangling out. There is a faint possibility that the two problems are connected by fecal bacteria settling on the vagina due to a hemorrhoid. If this is the case, you should treat your hemorrhoid condition immediately.
Most diseases of the vagina that can cause itching include bacterial vaginosis, herpes, gonorrhea and dermatitis. Except for dermatitis, most of the other conditions manifest themselves in colored discharge, odor and sores. Dermatitis is a skin disease that can be caused by an autoimmune disorder or a skin allergy. Surprisingly, the problem that you have mentioned is really quite a common one. The reason for the skin irritation near the vagina is the moist surroundings causing the bacteria to thrive in the area. This is a common problem that sometimes occurs in places that contain approcrine sweat glands producing a different kind of sweat that bacteria work on in order to create body odor. This is a possible theory that incidentally explains itching in the underarms. Solving this problem just requires a bit of disinfection of the vulva with regular disinfecting soap. Alternatively, to be absolutely sure, a wash with salicylic acid might be needed to remove dead skin as well. Another possible reason for itchiness is excess public hair that pokes into the skin. A trim would remedy this. The opposite condition of no hair can also cause this because a close shave can sometimes cause minute skin cuts. Remedying this requires that you apply some aloe vera topically and you should trim it instead of shaving. Therefore, the combination of aloe vera, salicylic acid and regular and thorough washing will solve an itching vagina. If it does not show results within a week, visit your doctor.
Hemorrhoid treatment is already a problem that has gone too far and that will require a doctor to destroy the hemorrhoid tissue that has been ejected from your rectum. In some cases, you could this yourself as well by lubricating a finger and then reinserting the tissue back into the rectum. Eventually, the inflammation of the tissue will disappear but you need to ensure that you have a high fiber diet to prevent the problem from recurring.