Okay, then I wouldn't ask that particular person for another ride. I find his comment rather rude. You can't drive and it's not by choice. All he needs to say is "I'm sorry, I'm not available to help currently".
What about grocery delivery for a time. You order online, they deliver. Many do it for free for patronizing their business, or a very small fee.
What about looking into one of those shared ride public transportation services for certified riders who are unable to use regular fixed-route buses due to disability or a health condition? Would that be a possibility for your remaining PT appointments? I'd think the office of your OS, or PT, would be aware of any such services in your area. Possibly something to consider to help you feel less of a burden to others.
Otherwise...if your church is small, would you be able to place a schedule of appointments you need rides to and hang it on a bulletin board, then those willing to help could sign up for a particular date? That would save you the discomfort in asking and whoever you're asking the discomfort in politely declining. Just thoughts....