Hey jmsolf! I'm sorry to hear that you have to go through the bitch that is Opioid withdrawal, but luckily, it's been done before and you're totally capable of it. Now, there is a very wide range of symptoms concerned with Opioid withdrawal and just as the drugs in question effect people in different ways, the withdrawal syndrome is often experienced in equally different ways. Some symptoms are much more severe for certain people, while some people don't even experience all of the symptoms typically experienced.
The only commentary I can make about the shortness of breath is that of the many symptoms involved here, anxiety, tachycardia (fast heart beat), weakness etc. are all common symptoms. I wouldn't find it strange to feel out of breath during withdrawal. It's hard just to walk up stairs when I'm sick and I definitely am out of breath by the time I get to the top.
Basically, I don't think that what you're going through is anything to worry about. It is entirely your call, but I think you're only experiencing withdrawal and it's probably not anything to worry about. However, I don't know you and I'm not a Doctor. If you feel that what you're experiencing is truly serious and beyond the normal landscape of Opioid withdrawal, then I would go see a Doctor.
Let us know if there's anything else we can help you with!