It sounds like your dog is having an allergic reaction, and has hives. He may have been stung, or bitten by something.
Try using Benedryl.
Stick with plain benadryl tablets (benadryl without added decongestant). The correct dosage is 1 mg per pound of the dog's body weight.
Benedryl is very common, and you should be able to purchase it easily, even at this time of night. Try a grocery store, a super mart, an all night pharmacy, or even a gas/convenience store. The bumps should start to disappear within an hour of giving the medication. You can give him another dose 6 hours later. If the hives do not go away, or if they do, but then comeback...You need to get him to the vet.
If at anytime, your dog is drooling, having trouble breathing,or if any area of his neck or head starts to swell, you need to get him to the vet ASAP.
If he starts to get hives on a regular basis, you will need to find out what he is allergic to.
This site complies with the HONcode standard for trustworthy health information.
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. Med Help International, Inc. is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.