I experience continuous spasms and cramping after orgasm which continues until I'm stimulated again It goes on for some time and can be frightening Does this mean I'm having another orgasm ? Or haven't finished the first one ?

I've seen/caused them. Yes, I do think they are unusual. I could visibly see my partner involuntarily contract in spasms containing 10-15 oscillations. I was also able to say "come for me" without touching and it would keep happening.

In looking at the mail counter part, where ejaculation takes place in spasms, I might call the series one of "your orgasms".

I'll also conjecture that the "cramping" is really using muscles that haven't been used much before.

The "second stimulation" is really "breaking the cycle". Sort of like if your head hurts and you step on your toe, now you head doesn't hurt anymore.

"Kegel's" or "Kegel exercises" might help you in the long to to strengthen those muscles, so it doesn't hurt as much. We really don't want pleasureable things to hurt, do we?

Find the muscles that can stop and start the urine stream and try to do 10 repititions of 10. Squeeze and let go about 10 x. Rest. Try to repeat 10x.

Females orgasm in different ways. Most have trouble getting there.

Males can orgasm without ejaculation or even without getting hard.

Females can be trained to orgasm on command anywhere.

Next time you are at your Gynocologist mention this. It may be nothing, but it's best to be sure.