Your concerns are genuine and anybody having such changes will feel concerned. Thanks for choosing healthcare magic to answer your concerns. The most common cause for itching lesions over the body are allergy
or fungal infections. From your description, it can be both of them, and can be confidently commented on only after observing how it looks and how it responds to the drugs. Its good that you are planning to visit a dermatologist
soon. Until then avoid contact with direct sun and as far as possible avoid touching the place cause it will get infected by lot of touching.
There is not much reason to worry as the problem doesn't appear to be a big one and will resolve with a 2 wk therapy at most.
Hope I am able to solve your concerns.