My son has had a cold (sinus congestion, yellow mucus/runny nose, cough) for 1.5 weeks. Was getting well but he developed a sudden fever two nights ago. 38.9C. Treated with cool mist humidifier , and alternating children s Tylenol and ibuprofen . Fever broke last night. Lots of sweating and chills overnight. This morning my husband discovered small raised red bumps on my son s inner thighs during a diaper change. Didn t mention it to me. I saw them just now and am concerned. His temperature is up again around 38.5C as well. He s 2 years old and is up to date on all immunizations including measels and chickenpox . Could this be fever blisters or dermatitis from sweating all night? Son is in good spirits and drinking plenty though not much appetite for food. I ve taken pictures of the rash, diaper on. Please advise.