Hello, Welcome to healthcare magic. Propysalic ointment contains a potent steroid. Long term use can lead to whitening and thinning of skin as you have developed now. Potent steroids should not be used for more than 3 weeks. You can use steroid free treatments like calipotriol, tacrolimus along with emmollients to keep the disease under control. If the lesions are extensive, you can try phototherapy which will also help in getting your normal colour back. Other options to control psoriasis is systemic medications like methotrexate, Acitretin and Cyclosporine. These are to be taken only under the supervision of a dermatologist as they are all toxic medications. As far as the white collar of your skin is concerned, it is difficult to completely reverse it. Try applying moisturisers like paraffion oil everyday after bath. Stop propysalic. Phototherapy may help. Hope this helps you.