I would no scrape back there. That's something that could cause discomfort overall. What other symptoms do you have besides appearance? Do you have a sore throat? You are saying that you had a bacterial throat infection back in December? Tonsilitis? Did you take antibiotics? White spots on your throat are not indicative of throat cancer. Here's the symptoms of throat cancer and you don't mention any of the symptoms . https://www.mayoclinic.org/diseases-conditions/throat-cancer/symptoms-causes/syc-20366462 White spots on the throat can be a sign of throat infection like you had previously. https://www.healthgrades.com/right-care/oral-health/throat-white-patches but in the absence of any other symptoms, I'd not worry about it. Gargle with salt water if you can which might help.