I have a rash that itch on my right big toe?

You can : Try an antifungal as fungus is common on the feet. If it is a dermatitis without a fungal component a steroid would be medication of choice. Without the ability to see the skin - those are plausible options.

Think fungus: An itchy rash on your big toe might be due to a fungal infection- athlete's foot. Other causes might include dry skin, dermatitis. Eczema among others. See a podiatrist or dermatologist if the problem persists.

I agree with the 2: Answers provided. If you don't see a noticeable improvement after 2-3 days of a topical antifungal, see a doctor. If you do, keep using it for at least 30 days, since fungal spores live for 30 days, otherwise, it'll come back.