I am wondering if you can tell us a bit more. Are you thinking this symptom has to do with having multiple sclerosis or with having a cold?
The first thing I would suggest is to ask your doctor about this symptom. It could be anything. In the meantime I can give you some information.
If you are talking about having speech problems during an MS exacerbation...I have experienced this. My words come out in bursts and I am loud. If you had a cold...this makes sense that an exacerbation may have followed (MS symptoms can occur when ill or running a temperature.)
I did find a forum you should look at where people discuss this spasm in the diaphragm and what they did about it. The people on this forum described it as painful. Some of the suggestions given there were to take Baclofen, Neurontin, or Lyrica or even sugar water. But again...I strongly suggest that you see your doctor to ask what is causing your symptom. This may be totally unrelated to MS.
On a web site called The Multiple Resource Center, they give information about breathing problems related to MS.
Here is a quote from this web site pertaining to a symptom called the MS hug. I wonder if this may be what you are experiencing:
"The only breathing difficulties I ever get are when I get the'MS Hug'.....it's so tight that I can't expand my ribcage enough to breathe properly so keep trying unsuccessfully to take deep breaths. I believe that I should be doing the opposite like people who suffer asthma and take shorter, shallow breaths through my nose until it has passed"
I am not a doctor...just another MS patient so I am just giving you the research that I have found. But please do see your doctor. It might be something serious and you won't know until you ask.
Thank you for your question!