Hi, Brendan.
I am a physical therapist, as well. I have treated a few cancer patients that have suffered from peripheral neuropathy. It's true that it may just have to run its own course, but that doesn't mean that while you're waiting you have to suffer or have compromised mobility. It sounds like you have classic foot drop, which is a problem with the peroneal nerve. The peroneal nerve is a branch off the sciatic nerve and becomes superficial as it wraps around the head of the fibula (just below the outside of your knee joint). Although the nerve is most likely being affected by the chemo treatments, it is possible in cases where people have lost a lot of weight and cross their legs often and for prolonged periods, tend to put excess pressure on the superficial part of the nerve, causing foot drop. Either way, you can get fitted for a custom AFO (ankle-foot orthosis) which is a brace that will aid in keeping your foot from slapping on the ground and improve your safety by helping to prevent you from tripping over your own foot. If your balance is really off, consider using a cane for a short while, until you feel more sure-footed. Physical therapy sessions can help, as well, but I'm sure you're entirely busy with a million other doctor appointments. In this case, you're fortunate to have a sister who is a physical therapist. She has probably already given you some suggestions, although it can be difficult to take advice from family memebers . As the saying goes, "First things first." and I wish you the best with your treatment. We're all here to help.
Be well,
Kerri