My husband has spasms after ejectlating how come? Is there a cause or am I doing something wrong?

We'll need a better description of what is happening to him. Here are a few things to consider.

Is this something that recently started with him, or is it something that has always happened to him?

Is it a whole body spasm, oe just in a certain area? Muscle? Penis?

How long does the spasm lasts? Seconds? Minutes? Hours?

Is it a violent spasm?

Is it a jerking motion or simple twitching?

How old is he?

This might or might not being happening with him, but I know that my penis is hyper sensitive (especially around the head area) when I finish, and I don't want my wife to move too much afterward for a few minutes or so. If she does, I have a tendency to flench which looks much like a person that tenses up or jerks during being tickled.

A mans body has just gone through a rush of things which leads to a violent type of orgasm, and aftward he becomes in a sedated mood. For a man, it's very much like his orgasm is feeling like a huge tornado ripping apart everything, and suddenly and immediately afterward there is a sudden peace. If a woman moves soon afterward before the man is ready or expecting it, it much like a sudden and unexpected crack of lightening durng that brief calming period while the penis is still going to the shrinking process.