@Fletch, maybe discuss it with your oncologist first, but you can use a cream called hirudoid for the phlebitis. You can buy I over the counter at the pharmacy and helps with symptoms, it also helps with the pain. I was recommended after I had phlebitis after surgery many years ago. It also helped the bruising go more quickly on my breast after surgery.
See this scholarly article
Topical analgesia with nonsteroidal, anti-inflammatory creams applied locally to the superficial vein thrombosis/superficial thrombophlebitis area controls symptoms. Hirudoid cream (heparinoid) shortens the duration of signs/symptoms.
All the the best with your nails! I have my fingers crossed 🤞
Michelle x