I have read your question,
is not any kind of disorder it is just a reflex reaction of your body is you need not worry about that.But let me tell you scratching done too much causes abrasion and bleeding of the tissues so hence that purple patch you said seems like a outcome of severe scratching .
Since the area was already damaged , a soft spot was created where these fungal infections may have started.
are fungal infections which are now can be successfully treated , i Assure you that you have only these two problems and nothing else.
I think you should consult a dermatologist
immediately for a proper medication and cure.
Since these fungal infections spread from person to person , i Suggest you to maintain a seperate towel , comb as well.
After the treatment i suggest you to maintain proper hygiene and use a clean towel and combs.
I hope you Get well Soon,