Hi
Welcome to the MedHelp forum!
The lesion looks more like an infection, bacterial or fungal cannot be said for sure. You can apply a local antibiotic cream and see if it helps. It does not look like skin cancer which does not spread by scratching. A side lesion can develop by scratching if there is infection. If it does not heal by local antibiotic then consult a skin specialist. Take care!
If you don't feel comfortable with what the other GP tells you, maybe consider seeing a dermatologist since they deal with skin problems specifically. The GP's may not know of possible tests that may be available because they are not experts on skin.
I think you should go and get a second opinion from the doctor, Because I dont want to say something wrong because it may just clear up in a few days and it doesnt look like skin cancer but i dont know for sure but well done getting it checked out anyway
Hope this helps
Emily