Hi, i think i know what you mean, does it just feel like someone has been sitting on your chest all night? im only 20 and i have had this several times, and the day after i ache a little when i bend over. I went to see the doctor and he said he had never heard of anyone complaining of this before, and if it doesnt bother me too much, then ignore it. If it gets worse or stops you from doing normal activities go back to him so i think id give you the same advice. Let me know if its the same kind of feelings you have as it would be nice to know of someone else with the same problem.
Hope you ok
xx