My nostrils are collapsing when breathe in post rhino, and the space between each nostrils is narrower. Can it be fixed?

It sounds like you probably had a reductive rhinoplasty with cartilage excision. As you noticed, this can lead to a pinched tip with nasal valve collapse. The key in rhinoplasty is cartilage preservation, repositioning, and strengthening through grafting in my opinion to aesthetically improve the nasal appearance and at the same time improve nasal breathing. Although you are only 1 week after surgery, which is nothing in terms of healing, it is rather unlikely that this will improve without a revision procedure (which most surgeons won't consider until 12 months post-OP although exceptions to this exist). Typically, nasal valve collapse worsens as time goes on, rather than getting better. Keep in mind, though, that it is difficult to determine what happened without having seen pictures, examined you, and knowing what was exactly done in your surgery. I suggest you see your surgeon to discuss this with her or him. For the time being, I suggest you adhere to the post-OP instructions you received and don't do anything unless approved by your surgeon. Make sure your surgeon performs cartilage grafting from the septum and possibly ear or rib. Best of luck!

Follow up with your Plastic Surgeon.  A revision may be needed.  Without seeing your before and after photos, it is impossible to know exactly what was done in your procedure.  Based on the information you have given, it sound like too much cartilage was excised which may have caused a pinched tip.  This will cause the symptoms you described.  Best wishes to you!