psoriasis or eczema

Last month I went to see a doctor because I had skin rashes on my neck. The doctor told me I had food allergy and he gave me a shot. The rashes had gone for a few weeks, but now it is back again. I hate it because it makes me uncomfortable. I tried to cover my neck with my hair, but sometimes it would not work. I thought I have psoriasis or eczema I am thinking to go see a doctor again. For the meantime, I bought an ointment at the store and apply it on my rashes. I am hoping that it will work and clean up my skin. If it would not work I have no choice, but go see a doctor again.