Unless you have medpor in the tip of your nose, the tip can be reconstructed. The medpor implant is most likely in the bridge of your nose. and not affecting the tip.
You should probably get several consults for revision rhinoplasty.
The sharp columella-lobular angle with a lesion at the exact tip, is very suggestive that a sheet of Medpor was cut and placed in the typical position for a tip graft. Although a block of Medpor was made for the dorsum, thin sheets of Medpor, had also been manufactured. Some surgeons used it, instead of septal cartilage, for Sheen-type tip grafts. I am sure most of them failed.
This needs to be evaluated right now.
Revision rhinoplasty is much more complex than primary rhinoplasty. It's a smart move to look for a specialist. Luckily, in the New Jersey/New York area, there are number of revision specialists. I would meet with a few before selecting your revision surgeon.
The Medpor may make things more complicated as it can damage some of the tissue inside your nose. Try to find a surgeon who has experience removing synthetic implants. They may need to replace the lost volume with more cartilage. In your case, I would avoid using a synthetic implant again. Safety comes first.
You would benefit from a revision rhinoplasty but only by an experienced rhinoplasty surgeon. I'm not sure why MEDPOR was used. There appears to be a lesion on the tip of your nose, which looks like a mole but is larger than your before picture which suggests that the MEDPOR may be causing a problem. I would advise you to see a board certified plastic surgeon with a lot of experience with rhinoplasty and revision rhinoplasty. Good luck!