Thanks for your question on HCM.
I can understand your situation and problem.
In my opinion, you are mostly having allergic skin reaction.
Itching,
redness and spreading nature of rashes suggest possibility of
allergy more.
Allergy can be due to anything like badsheet, pillow cover, inner wears, soaps, shampoo, night clothes etc.
So better to change your bad sheet, pillow cover. Wear cotton clothes at night.
You may need anti allergic and antihistamine drugs.
You may also need
steroid containing cream on skin lesions.
Since all these drugs are prescribed medicines, you need doctor 's prescription for them.
So don't worry, you will be alright.