Beach vs. itchy rash

My husband and I went to the beach for the weekend. Sunday I started to feel itchy, and that night I noticed I had little red bumps up and down my arms and legs. I took Benadryl and put aloe vera on them. It's Monday, and I am still itchy, and the bumps aren't as red but are still there. My neck has been especially itchy today. We came back from the beach Sunday evening. I didn't get in the water while at the beach. Any idea as to what's going on? Has anyone else experienced this? I'm 13 weeks. I left a message for my doctor, but I haven't heard back yet. Thanks!