Re: pain in solar plexus..where ribs meet???
Sounds like you are experiencing costochondritis. This is basically pain sensation in the soft tissue and cartilege surrounding your ribs, and is quite common in anxiety sufferers.
I have had this for over ten years and notice it particularly in the upper and lower ribcage, when I have been using the upper chest muscles for continuous activity, i.e. painting and decorating, digging, over-use of computer keyboard, and as in your case driving.
Do you hold the wheel with your arms lowered at the 3 and 9 o'clock positions, or are you a gripper with your hands towards the top of the wheel. If you are the latter, as I am, you will probably find that you have unwittingly built up a lot of physical tension and stress on your upper ribcage and itis most likely this that is causing the discomfort.
You mentioned that your ribs feel 'bruised' and quite tender to the touch. This is a sure sign of costochondritis which can produce some very sore spots - quite often you can feel as if you have been punched although of course there is no bruising. Costo is neither degenerative nor does it present any health threat but you will find that you may need to temper your usual activity when it flares up, as it will from time to time, until it eases.