Thank you all for your support and commends
Yesterday evening I took Mercy to a new vet. He was very friendly with- it is important to me- he looked at her ears both and gave us ear drop -surolan- then he explained to me three range of possibilities related to Mercy's skin. He took blood sample to rule out mange as her symptoms are close to mange. Meanwhile he gave us a shampoo -slides wash. He also gave Mercy a shot to calm the itching down to give her skin a rest.
By the end of this Friday we'll know if it's mange or not.