I think that the dog must have irritated a nerve by scratching, biting or causing some type of slight injury. Nerves heal very slowly and will usually get better on their own although it feels as if it takes forever. A way to test this is to put a cold pack directly on the area that pinches (only for 20 minutes at a time, can repeat in one hour). The cold "turns the nerve off"and the sensation should stop for a while.

If this does not work then think of a muscle spasm (like a trigger point or hard knott) that is pinching the nerve. This can come from many things and you may only feel the pinching athough the problem is really muscular. Cold would help this also and a massage therapist or a girlfirend with some knowledge of how to massage could help figure this out. Trigger point release massage would help this.

One final thought that is not very likely is that you have done some damage to a disc in your back in your thoracic spine area. This would usually cause much worse symptoms that sometimes make people think they are having heart pain. I do not think that this is what is wrong with you but I want to mention it in case things get worse.