hi Going by your history,, you have itching and rash involving your face, chest and neck...Now there are two possibilities ...either it can be acne lesions(acne corporis meaning pimples of body) or it can be a photosensitive rash.. Acne vulgaris is a common human skin disease, characterized by areas of skin with seborrhea (scaly red skin), comedones (blackheads and whiteheads), papules (pinheads), pustules (pimples), nodules (large papules) and possibly scarring. Acne affects mostly skin with the densest population of sebaceous follicles; these areas include the face, the upper part of the chest, and the back. Some people are sensitive to sunlight; this is known as photosensitivity. Photosensitivity may produce a rash, which is known by the general term, photodermatosis. Patients may not associate their skin complaint with exposure to light. It is not always the bright summer sun which is responsible; some people also react to sunlight in winter, and very sensitive subjects may even be affected by fluorescent lamps indoors. As in your case, only the exposed sites are involved, so you need to be sure if you have any degree of itching or burning sensation on exposure to sunlight,,,, And as far as doxycycline is concerned,,it is a commonly used drug for acne.....but at the same time this drug can lead to photosensitivity,,,so I would advise you to make note of both of these conditions,,,,and see what your symptoms resemble....and if you are still in doubt,then its always better to tale expert opinion,,,, Hope it helps.. Dr Geetika Paul