Silverex is basically an antibiotic cream which was prescribed so that your burn can heal. Now as your burn has healed with pigmentation, you need a treatment to reduce that. You can use any of the medicated pigmentation reducing creams or even go with spot chemical peels
with Glycolic or trichloroacetic acid
to reduce the pigmentation. I would suggest you to consult a dermatologist
for the same.Also use a good sunscreen with whatever treatment the doctor prescribes. Take care.