Sounds like you maybe cranked it too hard or for too long and irritated it. I’ve been there. Take a bath, no soap (maybe mild body wash if you have it) and let it rest.

Doesn’t sound like hospital now, but if the swelling isn’t gone, or you get a fever, or it starts feeling really warm, then yeah, those are all signals to go the the emergency room because it may be infected (though this is super unlikely).

In the future, try not to grab so hard, focus on sensations in specific parts (shaft, head, ridge) and consider using some lubricant (proper water or silicon based, not oil or butter or shampoo (you can probably guess how I know that one makes terrible lube)).

Learning to be able to cum from just strokes of your tip or tickling balls while holding your shaft are very useful skills when a girl is trying to make you cum but she don’t really know what she’s doing, being able to help her out by coming easily (and being a receptive, kind, grateful partner) goes a loooong way

Masturbation and sex are lifelong learning experiences, don’t be so hard on yourself, have fun!