What Causes Itchy Red Bumps In Inner Thighs,legs And Penis?

I am a 6'0, 22 year old 180 lb white male. I am a Marine, and I've recently returned from afghanistan about 3 weeks ago. 2 days ago, I went to a party at a friends house, just sat around a fire and caught up with old friends and what not. We weren't in the woods, just at the base of the woods in the grass. Last night, I noticed some very itchy red bumps. I had them on my inner thighs (about 4 or 5 per side) 2 or 3 behind my knees, and 1 or 2 on my calves. These itched terribly. I woke up this morning, and it had spread. I had about 3 or 4 more on my inner thighs, 1 on my back, and 2 on my buttocks, and 3 small ones around the shaft of my penis, and a few more on my legs. I scratched 2 of the ones on my legs today while I was outside and noticed they have a yellowish puss/liquid coming out of them. What could they be and how can I treat them?