Is a son considered disobedient for refusing to take cortisone, which is harmful to his bones, and is he sinful for being unable to go to the mosque except for Friday prayer due to his illness and excessive flatulence that prevents him from walking?

It is permissible to discontinue medication that is harmful and affects the bones, because one is not obligated to consume what is harmful, as the Prophet, peace and blessings be upon him, said: "There should be no harm nor reciprocating harm." However, it is advisable to consult a doctor to weigh the benefits against the harms. If the harm of the medication is confirmed, your refusal to take it is not an act of disobedience, because obedience is in what is good. You should seek treatment for excessive gas. If its emission is continuous and does not cease, you may perform ablution after the entry of the prayer time and pray with it. However, if it stops for a time sufficient for purification and prayer, then you must perform the prayer at that time, even if you miss the congregational prayer. If going to the mosque is harmful or difficult, there is no sin in praying at home, as Allah Almighty says: "So fear Allah as much as you are able" and "Allah does not burden a soul beyond its capacity."