Hello, my name is***** and I have over 20 years of experience as a veterinarian. I'm sorry to hear that your fellow seems uncomfortable and is favoring his front leg and howling and whimpering.
Have you checked the leg thoroughly for any obvious sign of injury, areas that appear swollen or that he reacts to with palpation?
Does he still want to walk and play?
Is he able to bear weight on the leg, but just tries not to?
If he doesn't have any areas of obvious swelling or injury, and will bear some weight it is likely he has a soft tissue injury. It may be related to nerve root pain associated with the nerves coming off the neck spinal cord or a muscle pull high on his shoulder or neck.
The best thing for these is very strict rest. That means no running, jumping, chasing toys and very limited stairs. Those are things that tend to cause the most stress and pain and cause the injury to linger.
You can also alternate hot and cold compresses on his neck and shoulder muscles for 10 minutes at a time several times a day. The hot compress decreases muscle spasms and tightening and the cold decreases inflammation.
I also recommend putting his food and water bowls up at shoulder height so he doesn't have to reach and strain himself to eat and drink.
Watch him for any signs of joint swelling, fever (rectal temperature higher than 103F), decreased appetite, bruising or worsening lameness.
He should be much better in 3 to 4 days with a soft tissue injury but I would confine him for at least 2 to 3 weeks and then slowly increase his activity level. Soft tissue injuries can take a while to heal.
If he remains painful in spite of strict rest and compresses then he should see his veterinarian for an examination, possibly radiographs of his neck and front leg, anti-inflammatory medication and pain medications.
If he is miserable this weekend and you cannot have him seen the only over the counter anti-inflammatory that can be used in dogs is buffered, enteric coated aspirin (like ascriptin). Aspirin does cause stomach and intestinal irritation and ulceration as well as clotting problems so should not be given for more than 2 to 3 days consecutively and should always be given with a meal. If you choose to use it watch for lack of appetite, vomiting, blood in the stools or dark tarry stools and stop immediately if you see those. Do not use aspirin if your dog has liver or kidney disease or a history of a sensitive stomach or clotting problems.
The dose for aspirin is 10mgs to 20mgs per kilogram of body weight orally every 12 hours (about one half of a 325mg aspirin for a 7 to 15 kilogram dog every 12 hours). Always give with a meal. Do not use for more than 2 or 3 days.
Be aware if you choose to use aspirin and it doesn't help your veterinarian will be limited on what they can give as there must be a 5 to 7 day washout period between different nonsteroidals or nonsteroidals and steroids.
Please let me know if you have any further questions.