Squamous cell carcinoma of the leg and groin lymph node lighting up on pet. So many questions!

Mamaof3

My husband has been fighting a large wound on his lower leg, foot for years. He has history of vein problems, chronic inflammation and tons of surgeries to try to correct. After continued pain, growth and constant bleeding it was finally biopsied. He was diagnosed with squamous cell carcinoma in October. He had 8 weeks of chemo and radiation. it left his leg in horrible shape and still doesn't look like it will heal. We were starting to move towards amputation and he started to have pain in his groin, night sweats and some swollen lymph nodes. At his first pet scan a few lymph nodes lit up but a needle biopsy came back negative for cancer. Since they have swelled up again he had another scan and more lit up and the original ones biopsied are bigger and more active. The dr is telling us that the nodes may need to be removed and he needs a below knee amputation. This is very scary because we are already worried about how his leg will do with all the vascular problems and now we are adding lymphadema. Dr told us it can cause complications with a prosthetic. This has been so frustrating because his situation is rare and I can't find much info on chronic ulcers becoming cancerous. Is it common to have lymph nodes biopsied later become cancer? can lymph nodes that light up on a scan still all be clear of cancer? Wondering if we should push for another needle biopsy before removing them. Of course if it has spread we know they have to go but worried for all the side effects. I have been reading and had no idea how complicated  the lymph node dissection recovery can be. My husband is 41 and a teacher. Any input would be appreciated!