My Chest Hurts When I Take A Deep Breath And

My chest hurts when I take a deep breath and I feel unusually ill. I am very tired and have no energy. This chest ache began on Sunday, almost like I pulled a muscle....I don't think I did though. I just want to rest and/or sleep. I am a very active 57 year old woman. I work on my feet every day and regularly walk my two large dogs. Could I have pneumonia?