Cough in older dog?

I have a nearly 16 year old female Jack Russell and in the last week she has developed a cough that I haven't heard from her before.

She has had problems over her lifetime with reverse sneezing but this is something different.

We have had kennel cough in our household with our Labrador 2-3 times but it's not that either. She never caught the kennel cough from our lab on any of those occasions and we haven't had it recently.

I'm starting to get worried about her. The cough is very on and off and sounds like she's choking on something but nothing seems to come up and there is nothing stuck in her throat.

She has never had any allergies.

She eats very well and is on a healthy diet, she sleeps very well, she still comes on walks with me and our other dogs too. Overall she is still in very good health. Last week she was at the vet for teeth cleaning, under anaesthetic and came through all of that perfectly okay.

I'm going to get her back to the vet for a check up in a few days time. In the meantime, I wanted to get some feedback from the DS if anyone has had an older dog start coughing suddenly and what the reason was. Should I be overly concerned at this point?