Pigeon that cant or wont fly - Help

Hi

We found a pigeon in garden two days ago what could not fly it appears to have no injuries, it looks healthy but could not seem to get enough power for flight above 3ft, at the time we have had heavy rain and strong winds so we thought it may just be wet and exhausted so we kept it indoors in a cage with water and seed it appears to be eating. We tried to release him/her yesterday but again only 3ft off the ground so we re captured him/her. We fed him/her again for 24hrs then released her/him this morning it flew onto the neighbours roof with another flock. We thought that was it until this afternoon when he/she was back hiding under the seat outside and we have since recaptured her/him. Any thoughts would be appreciated to why the pigeon apparently can only fly 3 to 4ft again.