I'm a 32 year old male. I've been experiencing chest pain when I lift my arms or bend them backwards (e.g. to put a shirt on). It feels like strained muscles located just below my collar bones, right across the top half of chest. It's not a sharp pain, more a burning sensation but when I try to stretch the area a little it feels fragile. Over the past few weeks, I have been exercising a little more than I usual but nothing particularly strenuous. I look forward to reading your response.