Bit by gnats on arm. initially, small red bumps that swelled for a day, now a week later small water like blisters that won't go away. help plz.

Hives?: Are the new lesions itchy? Papular urticaria can occur a week after exposure to insect bites, with some degree of sensitivity to insects. Gnats are not a common culprit, but certainly can induce a localized reaction if sensitized. Keep skin well moisturized and expect resolution in short time. If itchy, try cetirizine (read label), an otc antihistamine. See doctor if rash persists.