Your little one will be fine as long as you don't give another dose until you have heard back from 111. I would not be giving you any reassurance or advice if you were not already expecting a call back as you have no idea who any of us are, but as you have already told people you can trust, then I think it is ok to let you know that on this occasion your little one will be fine.
May I gently suggest that when any adult is looking after a sick child that there should be some sort of notebook or chart, that you all fill in immediately after giving the child their medicine. Keep it with the medicine bottle, or stuck to the outside of the cupboard the bottle is kept in, so it is always handy.
It is extremely important that all adults in the household, and who are caring for the ill child, know exactly when and where the medicine was given, and if there is more than one of you, also initial it in case someone needs to query something about the last dose. At the time, especially if we are the only adult dealing with it, we think we will remember what happened, but it is amazing how soon things can get muddled in our minds, so noting down anything that seems at all relevant is always a good idea. Also, if the child throws up within 45/50 minutes please note that down, and the rough amount of vomit, and any particular colours, consistency etc.
I hope that he feels better very soon OP, and that you can at least relax about the medicine already given, and I hope you both get a good night's sleep (yes it is fine to let him go to sleep if the medicine you gave him is your only worry). By the way, I am a grandmother now, but I know lots about making mistakes and having accidents with my children when they were younger, which is why over the years I gave quite a lot of thought about how to try and prevent as many as possible 'accidents' as they grew older - but nothing is foolproof, we are all human, and the more stressed we are, the more likely we are to make mistakes. I wish these were real 💐 for you xx
ps. Can you keep the Calpol and Calprofen seperated from each other in the cupboard you keep them in, just to give a little extra time to think about which one you want to give your child.🍫