I Was Feel Stiffness & Pain In My Chest Muscles

i was feel stiffness & pain in my chest muscles around my sternum bone specially right side since last 18 month this problem raise with decrease environmental temperature like i suffered more in monsoon & winter while in summer i never feel such problems my ECG reports & blood reports was normal i was visited to heart specialist Orthopaedic & MD medicine doctors but they didn't find any cause in my body to correlated with this problem M/30