little red bumps on my chihuahua

Question
my dog has red bumps all over him. we walked around the yard two days ago, the next day he wouldnt even stand up. that night I discovered all the bumps/welps. my vet said it was allergies (over the phone)I gave him benedryl today and they're still there.Unlike when my other dogs have done .they're bumps and symptoms went right away. but not his .what could this be????????           you can post my message.  

Answer
It does sound like an allergic reaction, or he may have gotten bitten by fleas/gnats.  I would recommend continuing the benadryl at a dose of 1 to 2 mg per pound of body weight THREE times a day in addition to baby aspirin (as long as he is not currently on any pain medication) at a dose of 5 mg per pound twice a day.  If the bumps do not go away in 48 hours, then he may need steroids.  You can also give an oatmeal bath to soothe his skin.