Allergy? After using a shampoo for years I randomly broke out all over my body but not my scalp. After many tests and 2 biopsies and 3 months of this itchy rash I found out my hormones had changed. I ended up having an allergic reaction to 7 different things at one time. It was all a chain reaction that apparently began with the shampoo. They even tested me to see if it was an allergic reaction to the sun. (It wasn't.) Before that, I never had a rash or sensitive skin. Now I break out to everything. Finding the cause is the hard part because it can be the smallest thing that you may not realize. They say to recall anything you've used over the last two weeks before it began. The small things are hard to remember. A new cleaner brand, new makeup, new air freshener... I've been allergic to things that normally nobody would think about but it caused an allergic reaction. Like an air freshener. It doesn't actually touch your skin so it's not really thought about but it gets in the air that surrounds your body. I used a new chapstick once. Had used the brand for years but tried their new flavor that was berry and that caused it. I spend lots of time with the dermatologist. lol. If it is an allergy, it won't go away until the product isn't being used anymore. Since then, I've also been allergic to the hormones I produced while pregnant. Had it my whole pregnancy and it was literally gone within a few hours of having my son. It's amazing what causes itchy rashes that you never thing about normally.
A rash that appears on the body and looks very similar to roundworm and causes itching is Pityriasis rosea.
For the severe itching, you can apply calamine lotion and also take an antihistamine.
Although it is difficult no to, do try not to scratch. Scratching causes the itch scratch cycle and can make it much worse.
Avoid using irritants such as soaps with fragrances, hot water, wool, and synthetic fabrics. You can use mild soaps that are also moisturising. Applying moisture creams specifically for sensitive skin may help the itching due to the dry patches.
As the Nizoral cream and tablets have not worked and the condition has worsened it appears that this medication is not lessening the problem. I would suggest that you see the doctor again and ask whether your rash is likely to be Pityriasis rosea.
Ringworm is a fungal infection. As Nizoral is an antifungal medication and if you have used it for 1-2 weeks and it has not helped, then it would appear that your condition is not a fungal one.
Best wishes.