Trapped nerve!

I recently started doing light strength training at home along with videos on youtube, I ten do my usual cardio too, on on Tuesday I did my workouts and after wards like and few hours later my lower back started feeling uncomfortable.
I have since been taking painkillers and doing back exercises sent to me in a link by my brother (he is a doctor).

When I do the exercises I feel better for a while afterwards but if I am on my feet in the kitchen for a while the twinge starts again.

Any advice would be greatly appreciated. I know what the doctors will say, they will print out the sheet which I have already and say take Ibuprofen regularly which I am doing already.

Thank you.