Stop!

Playing shouldn't be causing "pain". Aches are normal at times, but not actual "pain", which could be an indication of causing damage to your hands.

Try doing this exercise starting on the 15th fret (or even higher up the neck) and see how that feels. You can then move down to the 14th fret after a couple of weeks, then the 13th and so on. If you started higher than the 15th fret, then just move down one fret from wherever that was.

Don't be in a rush to try starting from the first fret. Your hands might be too small to enable that, but it won't stop you from learning to play.

Don't worry if you can't manage four fingers from the start. It took me months to manage that, and I have large hands. And only spend a few minutes on this, resting your hand afterwards by laying it down on a flat surface, fingers spread slightly and completely relaxed.

Trying to do too much, by trying to stretch your fingers beyond what is possible could permanently stop you from playing.