How to relieve lower back pain?

We just got back from vacation last night and the trip was around 10 hours. My lower back started hurting and when I woke up today and still now it feels really achy on the left side and like a locked feeling. What can I do to make it normal? So aggravating lol. I’ve tried a heating pad and with the massage option turned on it as well. It’s like I can’t even stand up straight either