Thanks for the extra information. If he turned very quickly on this foot and immediately yelped then it may be something as simple as a twist or sprain of a muscle or of the wrist joint. Often these things will be really sore for a couple of days and then start to improve, although rest is the key with any lameness, and that's not always as easy as it sounds. However, if he is not putting any weight on it at all then it would be worth having your vet have a look at it - they should be able to localise the pain and see of anything feels unstable, and even x-ray of they are suspicious of a fracture, however it does take quite a bit of force to cause a fracture of a bone in a mature dog.
Until you can get her to the vet, keep applying the cold therapy to it if she will allow it, making sure that the ice is wrapped in at least two layers of towel to prevent burns to the skin. Try to keep her very quiet, by sitting with her yourselves, restricting her to just one room, barricading furniture she can jump on etc. If you are sitting down you could even put her lead on so that she stays next to you!
Without examining her it is difficult to say exactly what is going on. The benadryl she has will sometimes have a slight sedative effect, but don't give any more than usual. At your own discretion, you can give a little human aspirin to her to try to make her more comfortable. This is really the only human drug I can suggest, and be aware that technically no meds should be given without the supervision of her own vet as there are some dogs that can have adverse reactions. In order to give the safest possible dose, you will need to weigh her as accurately as you can. You can then give aspirin (and only aspirin, not a remedy that contains any other drug) at a dose of 5mg per lb bodyweight, so if he is a small wheaten you may need to use baby aspirin and you may need to divide a tablet. For example, if he is 10lb weight, you will need 50mg aspirin, so half an 80mg baby aspirin is plenty. If in any doubt, give the lower end. If you're not sure what to give, let me know what weight she is and what size of tablet you have and I'll help you.
If you are going to the vet tomorrow, then give only one dose, and this should always be given with food to avoid tummy upsets.