Make sure you take it easy on deads and squats till your back gets better. I deadlift in the 600s and strained my back a few months ago warming up with 315. There's times I've strained my back maxing out. It happens to everyone eventually, what's important is for you to back off the weights. Till your back to normal in the mean time do 15 mins of stretches for your lower back before and gym sesh and after a gym sesh. That's honestly what helped me. 2 weeks later I started deadlifting again and if I felt discomfort I just backed off. Started at 225 dead world my self back to 605 8 weeks later. Ppl tend to over do it all the time and not know it. Its important to listen to your body. Make sure to go to the chiropractor as well that helped tremendously too.