It is very important that you start with a medical exam. There could be a medical reason for this happening. Also talk with her about adequate wiping, tho I doubt that is the cause. My 9 yo daughter does not wipe. she does get poop in her panties but not so bad that it smells.
If she is leaking urine and/or poop it is most likely a medical problem that can be corrected.
I would also have her take a bath every day or every other day at least. And be sure that she is changing her panties every day. Most odor becomes stronger over time. If she wets her outer clothes she needs to not wear them again. If she can't smell herself ask the doctor about that also.
Wearing diapers is not an option. It would be demeaning to her. She needs to feel good about herself so that she will take good care of herself.
When I was around 10, my mother and aunt asked me how I took a bath. It turned out that I wasn't specifically washing my pubic area and I did have an odor. It is also possible that I was maturing and my body was putting out secretions that have an odor over time. Some girls do begin maturing sexually at 8.
Most important first step is a bath daily with clean clothes daily while you wait to get in to see the doctor. Also be sure that she has clean sheets and bedding. If she's leaking in the daytime she's probably also leaking at night.