I'm not a professional - but from everything I have read and experienced myself via physio and osteo, if you have tight muscles which cannot be stretched you probably need some "release" via massage - look for someone who practises myofascial release or trigger point therapy. Sports massage therapists use these techniques as do some physiotherapists. Ultra tight muscles may be "locked" into being contracted - and will react AGAINST stretching.

Alexander technique as someone suggested is also all about release, but works in a very gentle, quiet way, aiming to help you release tension and correct posture without forcing or stretching anything. If you are someone who experiences a lot of emotional tension - or are stressed - you might want to have some sports massage to get some release first, then do the more gentle work such as Alexander Technique which takes longer but is aimed at the cause of the issue.

Good luck.