Dermatology Questions? Ask an Online Dermatologist.
Do you start any medications before the rash started? Itch or pain? Any other symptoms? Are you aware of anything which might have triggered it? Any medical problems? Any surgeries? Any medications? Does anyone around you have similar problem? Any family medical history?
It seems to be scarlet fever rash. Scarlet fever (also known as "scarlatina") is a diffuse erythematous eruption that generally occurs in association with pharyngitis. Development of the scarlet fever rash requires prior exposure to S. pyogenesand occurs as a result of delayed-type skin reactivity to pyrogenic exotoxin (erythrogenic toxin, usually types A, B, or C) produced by the organism.
You should see a doctor to have exam and antibiotics such as penicillin V if it is scarlet fever.
Did you use a hot tub?
I see. It seems to be Seabather's eruption. It is due to skin penetration by Linuche unguiculata, Edwardsiella lineata, and probably other larvae of the phylum Cnidaria, which are found in oceans (salt water) . The tiny jellyfish larvae release nematocysts and inject toxin. The distribution of the lesions matches areas covered by a bathing suit, wet suit, or points of pressure (eg, wristbands of diving suits, flexural areas). Skin lesions are inflammatory papules, often becoming vesicular or pustular. Many descriptions have been reported from the Atlantic coast of North America and from the Caribbean.
Treatment of seabather’s eruption is symptomatic and typically consists of oral antihistamines (eg, diphenhydramine, hydroxyzine, or loratadine), topical antipruritic agents (eg, calamine lotion), and low (genital) or medium potency (trunk or limbs) topical corticosteroid preparations. Oral corticosteroids (eg, prednisone, prednisolone) may be necessary in severe cases. The skin lesions typically resolve spontaneously in one to two weeks.
It doesn't look like fungal because there are many pustules.
no blood test. The diangosis is determined with the medical history and clinical symptoms. You should apply over-the-ciunter 1% hydrocortisone cream 2 or 3 times a day for 1 or 2 weeks.