Dear Bodey,
I have sent a personal message with some other possibities, but can kick around a few mechanical senarios here for you. [sm=1syellow1.gif]
Also, without your location in you profile, I'm unable to look up an osteopath in your area, but you can check Yellow Pages in the General Osteopathic Council box. By law all osteopaths have to registered with them anyway, so I don't even know why we still pay for this box - I digress. [sm=banghead.gif]
The pain in the lower thoracic area, may well be a simple facet joint (small paired joints at the back of the spine) irritation or irritation of one of the joints between a rib & the spine. Your doctor will have been more concerned that it isn't referred pain from one of your internal organs & presumably checked you out for that.
And as said above an osteopath could sort that out for you.
The irritation in this area may have made your system reluctant to use your diaphragm properly for breathing, as this would aggravate the joint/s in question. So you may have adopted 'upper rib' or 'stress pattern' breathing with your upper ribs. To maintain this pattern of breathing, the body recruits what are known as the accessory muscles of respiration.
These include the pectoral muscles at the front of the shoulder & attaching into the upper ribs, the scalenes & SCM at the sides of the neck to first few ribs & collar bones. [&:]
The significance being is that some of the above muscles, if overused in this way will tighten & shorten over time & can cause a condition called 'thoracic outlet syndrome' of which there are at least 3 types. In short it means that they start to compress the nerves & blood supply to the arms, causing numbness in either or both sides. Again an osteopath should be able to help you sort that out too & check for other possibities, such as cervical ribs (extra, short ribs that can occur in the lower neck), etc.
Stress pattern breathing, either 'breath holding' or 'chronic subclinical hyperventilation' (longterm overbreathing that isn't obvious when examined) can effect the pH (acid-alkali) balance of the blood & gut. This can encourage non friendly bacteria ( often referred to as candida species/albicans) to overrun in the gut. This will starve your own sytem of nutrients including some of the B vitamins, which may result in an inability to relax properly & keep the whole thing going. Have written on this elsewhere on HP, so won't go on. [:-]
A young lady I treat had simillar symptoms & she discovered that avoidance of alcohol, sugar & MSG resolved the symptoms. Such sensitivities seem to be common & a relatively new treatment in the UK called NAET may help to desenstise to these. See links page on Holistic Centre site below.
Well I think I'm done for now - hope you find your answer soon.