Does weakness come and go?

All during dads illness (congestive heart failure) weakness came when his weight was up and his ankles was swollen. we would go in for IM lasix and the next day he's be released. This time, his ankles are not swollen, his weight is not up, yet he can hardly walk. He says he doesnt feel bad, has no chest pain, but i dont know whether to encourage him to continue to try walking or give in the wheelchair. Any suggestions?