Have Boot Prosthetic To Support Tibial Tendon Tear. Feeling Itchy. Developed Rashes. Applied Neosporin. Remedy?

Hi- I have a boot prosthetic since January to support a posterior tibial tendon tear. It has been fine up until 5 days ago when I had itching start in the area that the boot covers on my lower leg. It became more itchy and developed a red rashy area, but only where the boot lay against my leg where there was no sock between the device or my leg. I placed a cotton wrap between my leg and boot to break contact but didn't notice a worsening of the rash or itch, but it didn't go away either. I ceased using the boot around the house, kept the area clean and dry but it continued to itch and stay a blotchy red. Yesterday I put neosporin on it in one area and today it looks better where I treated it, but is still itchy and slightly red in the untreated area. I am diabetic, so I am very careful about my legs an feet. I have had no signs of neuropathy and this came on suddenly. We have been experiencing hot dry weather in the Seattle area, and I was wearing the boot for an extended amount of time each day until 2 days ago when I tried the abstention method to clear up the rash. What can you tell me about this issue? Is it likely to have been caused by the leather and heat, should I continue to treat with the ointment for another couple of days to see if it will clear up more? I need to schedule an appointment to see my PCP in October, so can have her double check on the progress of the healing too.