What Causes Burning Pain On Top Of Breasts And Under Arms?

I am a 30 year old female. No major medical problems and am a healthy weight. I am having severe burning pain on the tops of my breasts and under my arms, mainly the left arm. The pain started a few days ago and felt like a really bad sunburn. The pain is now a burning throbbing pain. I have also been running a low grade fever and been feeling very tired. I cannot wear a bra and even wearing a shirt hurts me. I have no rash, reddness, bruising ect. Thank you for your time.