Thank you for the additional information.
I am sorry to hear that Onyx is not feeling well. Benadryl can cause some side effects to dogs such as lethargy, drowsiness, vomiting, diarrhea, and loss of a normal appetite therefore I would be concerned that he could be taking too much Benadryl and/or he is having a reaction to the medication. Other potential causes of his symptoms would be:
- Ingesting something out of the ordinary that has caused an upset stomach
- Eating a foreign object that has become stuck in his stomach or his intestines
which is an inflammatory disorder of the pancreas which can make dogs quite uncomfortable
- An organ disorder such as kidney or liver disease
- Acid reflux disease
At this time, I would recommend decreasing the Benadryl dose to every 12 hours instead of every 6 hours. This should help with some of the symptoms that he is showing. Since he received a steroid shot he really should be fine and not need as much of the Benadryl to help him get through the allergic reaction.
You can also give some pepcid AC to help with the stomach discomfort. This is very safe and virtually has no side effects. I would give him 5 mg for every 25 pounds of weight every 24 hours. This medication usually comes in 10 mg per tablet. You can get this medication from a local drug or grocery store over the counter.
If he is holding down liquids then you can feed him 8 hours after the last vomit. By holding him off of food this will help his stomach settle down. My recommendation would be to feed some boiled ground beef or boiled chicken
breasts with cooked rice. Two parts rice to one part meat. Feed this until he is back to normal. This is very easy for him to digest and should help reduce inflammation in the stomach/intestines.
Overall the Benadryl could be causing his symptoms, though he may also have developed quite a bit of an upset stomach from a different case as I suggested therefore I would start the pepcid and decrease the Benadryl to help him get through this. If he does not seem to be improving in 24 hours, I would contact your vet for more help.
Hope this helps to answer your question - if not or if you have any more questions please feel free to reply by clicking on the "reply to" button. Thank you for your question!