What to do if i've been diagnosed with impetigo but looks like ringworm?

Impetigo : If you've been given medicine for impetigo, and it's ringworm, the medicine won't work. Impetigo is a bacterial infection, ringworm is a fungal infection. If there is no improvement in a couple of days; have it rechecked.

Follow instructions: Rashes and other skin lesions are sometimes difficult to definitively diagnose because many of the features of different conditions can overlap. It's best to follow the instructions of the prescribing physician, who is highly trained and experienced. If your rash is not improving after a good faith effort of treatment, other diagnosis should be considered.