It is permissible for a sick person to join prayers, so he may join Dhuhr and `Asr, and Maghrib and `Isha’, at the time of the earlier or later prayer, depending on what is easiest for him. Difficulty caused by sickness is one of the excuses which make it permissible to join prayers.

Passing wind breaks wudu but if a person passes wind continually, he has to do wudu for each prayer when he wants to pray, then if wind comes out of him whilst he is praying, that does not invalidate it.