Is this a suture underneath my skin? (Photo)

Yes - it looks like a Prolene or Nylon suture.If so, it won't dissolve, and should be removed in case it gets infected.
That shouldn't be a problem - Many surgeons (including me) never use such sutures, for this and other reasons). I use a suture that will dissolve in 6 months (PDS suture), for Rhinoplasty, as well as some short-stay sutures. Scarring will hold the cartilage in place, and this should be fairly straightforward to remove, just in the surgeon's chair. I suggest you go back to your surgeon,

The picture of the inside of your nose appears to show crusting, which is relatively common only 10 weeks after rhinoplasty surgery. If the black, hair like structure is what's bothering you, the best thing to do would be to bring this to the concern of your surgeon. It may just be a dislodged hair. I hope this helps! Sincerely, Dr Joseph

It looks like it could be a suture. The only way to know for sure is to have a doctor look at it. If it’s a suture it can be removed

Most rhinoplasty surgery requires closing incisions using absorbable, and or permanent sutures.
Surgeons are obligated to take care of patients after surgery. Not doing so it is considered abandonment. If the surgeon feels the patient is no longer appropriate for that doctor patient relationship, then they are obligated to transfer the care to another provider.
I suggest you go back to your surgeon and ask them to give you appropriate, postoperative care, and consider why there was a breakdown in the relationship.
Posting questions on real self is a poor substitute for proper postoperative care.
Best,
Mats Hagstrom, MD