I have slightly bigger than pimple size, red, very painful bumps on multiple areas of body (both sides). The skin within an inch around them is also very sore. It feels like a stinging pain, but it also hurts like a deep muscle ache. I haven t changed anything in my daily routine as far as soaps, detergents, etc. I was recently at the beach in North Carolina and spent most of my time in the ocean. I also used a pool and a hot tub for a minimal amount of time. Some of these bumps almost look shiny like a blister and have a head to them. They have nearly doubled in size since discovering them this morning. I have 5 on my shoulder all within 1/2-1 inch apart, 5 scattered on my abdomen, 2 on both sides about 2 inches under my armpit and on my rib cage, one on my bicep and another on my forearm on my inside elbow, and two close together on my hip. What can they be?