Nowadays, I myself prefer natural things because it is not only the doctors who are mostly not trustable but also medicines. So I write to you some facts about a few natural things. From your history of your symptoms, I couldn't clearly understand the disease. Only symptoms are not sufficient to diagnose a disease. Examination and then if needed investigations are also required. Therefore, I will write to you the use and benefits of some natural things and then you will judge yourself what will be better for you.
Generally speaking, ring worm is very clear to be diagnosed but I had seen an advanced case whose back skin had become very thick and red. If medication was given then it would be a long time treatment which also has many side effects. But Allah has given great qualities to lemon. So the local use of lemon on his back for a few days (twice a day ) would be sufficient for the treatment. Also you must always remember that the real shafaa (cure ) is with Allah. If you only start the Ruqiyah which consists of reading surah Al-Faatihah + the last three surahs, repearedly, blow on water and your hands and pass those hands on your face praying to Allah azza wa Jall for Cure, also if not troublesome then washing face with the water on which you have blown the ruqiyah, will be better. Always, read salaat wa salaam on Muhammad salla Allaho alaihi wa sallam between Ruqyah and Du'aa i.e after Ruqyah and before du'aa for cure. This Ruqyah may be sufficient but Allah Ta'ala wants us to take a cause along with du'aa. So you, now should think, if it is an advanced case of ring worm then you should start using lemon+Ruqyah and du'aa.
In case of ringworms: there is itching and slight burning. A red ring can be seen but that is in the beginning. But when it advances then thick, red skin not like normal skin is seen..
If it is not like a case of ring worms, then I suggest you to use Turmeric powder. Allah All-Mighty has given it unique qualities. What I write here is on the bases of experience. Turmeric is anti-bacterial, anti-fungal, anti-helminthic and even anti cancer. Its anti cancer effect, I didn't check while the other three effects are confirmed by the Grace of Allah. It is said to be anti-cancer too and I hope so.
Thus, you should moderately heat a little good oil (olive oil is good) and in it mix turmeric powder as much as to make a paste. Then apply it to your face at bed time and wash it in the morning. Do it three times in a week (better on alternate nights) and then wait to see the result.
Important notes:
While using lemon or Turmeric on your face, you must protect your eyes. Also keep away from the nostrils.
Always combine the application of the remedy with Ruqyah +salaat on Muhammad salla Allaho alaihi wa sallam+du'aa with humbleness.
May Allah give you shafaa, aameen.
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For washing the face, you should use simple water. Avoid using soap etc.