I have the feeling I’ve always had a weak back.
Some 4 months ago I started working out regularly. Now I can almost touch the floor with my hands without bending my knees.
While doing this exercise I heard a small crack on my back, nothing serious.
Since then I can lift weights easier than before but my back still hurts a bit. My back doesn’t hurt as much after coming home from work, which was normal before.
What else could I do to have a stronger back?
This, a thousand times. Also echoing what someone below said that a physiotherapist may be best, but in my country, the doctor refers to a PT.
The reason why getting proper medical input is important is because often back pain arises because of long standing, complex imbalances e.g. I had a weak core, which caused my legs to lock in a way that sort of compensated, which caused me to have an odd gait and to fall lots. Generally improving your strength was a good step, but if you’re experiencing pain like this, you may need help in identifying any underlying weaknesses.
Especially because injuries don’t just come from heavy or intensive exercise. I knew someone who had upper back pain that likely stemmed from poor posture. They identified the muscles that were painful and started doing stretches to that area. Even though it was only light intensity stretching they were doing, they were inadvertently exacerbating the root problem, which they didn’t learn until they had to be seen by a doctor urgently.