Possible reaction?

I bought some sculcap and valerian for the boys with the impending firework season upon us, as Indi isn't stressed by it but does go all' me Tarzan you Jane 'and barks in protest. This however does set Phoenix off and he's an anxious chap at the best of times.
I started the boys on Saturday morning, Phoe had 3 doses and Indi just 2 as his need is not as great, last dose at 6 pm, by the time i got home at 10pm, Indi had had a severe coughing fit, he coughed intemitently all through til monday lunch. I stopped the tabs for him and within 4 hours his cough had dissapeared.... Bizzare, So it just makes me wonder if it was the tabs , as it came on when he started them and stopped when i stopped them??
Phoenix is fine no cough in sight
what do you think?

Is he a heavy self groomer? This time of year they are molting (for lack of a better term) to get their winter coats in and Rufus will cough after heaving grooming sessions from what the vet described as a "hairball" and was nothing to be concerned about. Could this possibly be the culprit?

yes he is Lora, it just concerned me that it started at the time i gave the meds, he has coughed since on occasion, so hopefully it is hairball.

I bet that is the issue then. I was concerned Rufus was developing cardiac cough and the vet said it sounds differently. Lets hope thats all it is, and sounds like it probably is. hugs