Suggest Remedy For Itchy Rashes On The Penis

Hi, I went floating down the river two days ago and since yesterday morning the bottom side and base of my penis and testicles and even a little bit on my penis head has a red velvety splotchy looking rash on it and it itches SO bad. At first I thought that it was just dry and irritated from rubbing against my jean shorts and being wet and getting on and off of our rubber raft (which it still could be) but it just seems far too itchy and red and velvety now to be just dry and irritated. Might it be related to constant irritation from rubbing up against wet jean shorts, or could it be some sort of fungal or bacterial infection? And if so, should I get some sort of hydrocortisone cream or something else recommended by you? I ve been putting aquaphor on to help heal the dry symptoms but so far there is just no relief. Its just warm and incredibly itchy. What should I do?