Hi there!
I'm assuming i know what whipcreaming is so i wont ask and wait for a reply.
Okay, now knowing his age and knowing there are sensual rules and that this is a sensual relationship, i think i might be able to help a tiny bit more.
In this situation, since this is sensual and more intimate sexually, i should be able to give a few more ideas.
I'm not sure if he lives alone or wears diapers or pull-ups but i will give punishments for those too just in case.
Haveing lots of ice in his diapers/pull-ups or a big, cold icepack to put in his undies for a certain amount of time of your choosing, refrezzing to keep the punishment going for longer if necessary. Ice has been known to keep boys from having erections and it's uncomfortable when it's too cold so it's a good punishment to use.
Another one could be urine holding or releasing. Basically you could tell him to pee or poo himself regardless of what he is wearing. If its holding, his punishment would be to hold it for a certain amount of time and if he can't take it then he will wet or mess himself. This punishment is a bit more extreme and may not be used if your little isn't into un-contained urinating or what I believe is called "watersports" but i am not sure if that term is true. Same for un-contained messing (un-contained meaning not likeing going potty without protection).
Obviously writing lines is universal so this method can be used if you want.
Taking a cold bath is another, much less used punishment but still effective.
Enamas, suppositories, or laxatives are effective regardless if he is wearing padding or not.
Diaper punishment is just forcing your little to wear and use diapers. You can make it so your little can't change until the diaper is full or until he gets a small rash. This punishment can be until a package of diapers runs out or a given time frame.
The last one is just one that came from the top of my head, forced whipcreamies. The opposite of what you did but he has to keep doing it constantly even when his arms are tired for a certain time. Think of this punishment being when a parent found their child smoking so they made them smoke the whole pack at once.
I don't do well with sensual relationships but you do have to remember that he can't be little 24/7 and he may get to busy to be able to say anything. He could tell you he was gonna be busy but sometimes things just come up.
Personally, i don't think a punishment was absolutely needed for this situation but at the same time, i don't really think it was that harsh of a punishment at least from my point of view. Light scolding probably would have been the best punishment for this case, and tell him that you worry about his safety and want to know if he is okay. As the role of a caregiver, you should be the one to check on him, not necessarily the other way around, however, he still should check in with you as well, especially when he is going to be busy, then he should let you know. The punishments i gave you above are for much bigger reasons then not responding for a long period of time, keep that in mind.
I myself am a little and i know how important long distance communication can be, as communication is what keeps a relationship going.
Also, if you don't have punishments related to actual children, then that takes away from the whole "little" feeling, so make sure to punish him for not eating his veggies or cleaning his room because these are much more important then not talking to you for a few hours.
I hope I didn't fry your brain with all this reading and i hope I didn't offend you in any way since i only wanted to help.
~sincerely your friendly neighborhood baby boy
rleqh99 or Jordan
PS: tell me what you think about my reply. Anything you agree or disagree with?