Sunburn and pregnant!

I got a really bad sunburn on my shins at the beach the other day. It was so painful the night of and then today, just as painful but I looked and I have a few big blisters on my shin. I didn't realize how bad it was, I was told as long as you keep your core temp low and take cold showers it won't harm the baby but now I'm worried. We just had a doctors app today and the baby was wonderful! I'm still a little worried, & in a lot of pain! I'm currently almost 20 weeks preg