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You need to investigate this properly.You should first get a KOH examination done for fungus.Usually fungal infections are seen on one foot only .Associated with itching and burning sensation.In such a case you should first take an oral anti fungal tablet along with the cream and notice the difference .If in initial 2 weeks you respond good then you should continue the medicine for another 2 weeks .This would completely cure the lesion.
If you don't respond to this then probably you have an eczema
,which needs topical steroids
And if you still don't respond ,then you should get a skin biopsy
done to rule out any tubercular infection
For all this you need to consult a dermatologist
who can assess your problem and treat you.
I hope this answers your question,if you any further query ,i'll be happy to reply.