I feel pain in my lower back when i finish my exercises in gym. what should i do for relief?

I am going gym regularly and doing exercises with waist belt.Once I lifted 70kg wt without any belt and that also 5-6 times. After 2 days I started feeling pain in my lower back. till now I am feeling that pain but not of that much.Now i always wear the belt while doing exercices. Should I consult the doct? or it will disappear itself.