She may be having a mild to moderate amount of post vaccinal inflammation or a mild vaccine reaction. This can be common, especially in the smaller breeds.
Since she is just acting achey and tired, we can definitely give her some over the counter meds to perk her up!!
You may use either Children's Benadryl( 12.5mg/ml) or adult strength benadryl(25 mg) as an antihistamine.
Give 25 mg of benadryl by mouth every 6 hours today to fight inflammation at the injection site and tone down post vaccinal reactivity. This will make her sleepy, but it should make her feel better overall! Benadryl can make them vomit occasionally, so watch for that in the hour after you give the meds.
You may use the generic benadryl, it must be diphenhydramine Hcl 25 mg only...no other cold meds mixed in with it!!
You may also give her an 81 mg strength Buffered Children's or adult 81 mg aspirin every 6-8 hours today to relieve any actual pain she may be feeling. Aspirin should be given with food, and I would only give 2 doses at the most until she is feeling better.
If she develops any signs of facial swelling, difficulty breathing or the onset of hives, you will definitely want to continue the benadryl and get her into a vet as soon as possible
Hope this answer helps you today as she try to make her feel better! Remember to ACCEPT! Best wishes, Dr. Smith. Feel free to PM me with updates!!
Veterinarian
Veterinarian in Small Animal Practice for 13 years