I have to take Cory in

I have been on hold with the peds office for over 20 minutes now. I was going to ask them the best thing to do.
Cory can't walk at all now

I will have to take him somewhere I can bring a wheelchair out of. I really don't want to spend my whole day in the ER (especially on a Friday) but I don't think he can make it into the peds office without a wheelchair and I'm not sure they have one.
How do Urgent Care places work? Do we just walk in? How about insurance? Is it an office or ER co-pay?
Any insight would be appreciated.