Pigeon - Poorly?

When I arrived home from work I noticed this pigeon sheltering from the rain under the tree in our garden. My parents had stopped off at ours on their way to Manchester and they said it had been there a while. After having had tea we chilled out in the back room and the pigeon was still under the tree . It was pacing around the tree and from side to side and continued to do so until dark. He just seemed so sad and lost; is this normal pigeon behaviour?