Neck/chin Lump 2 Months Post Face-lift? Felt Pop After Sneezing Attack

Generally speaking, it can take 6 to 12 months to completely heal after surgery. Please keep in touch with your surgeon or his/her clinical team to discuss your ongoing concerns.

A face lift and neck life requires a significant amount of deep sutures.  A coughing fit may have caused one to pop which could be very insignificant. The lump you describe as possibly a gland is usually not seen well before the facelift is performed because the skin is loose. However,when all the tissue layers become tighter, the gland can become more obvious .  Surgery doesn't change this unless they are partially removed which is very controversial .

It is very difficult to answer your question without seeing you in person and examining you - please follow up with your surgeon or seek another opinion

Without examinating you and touching the area of concern, it is difficult to judge what exactly is going on.

A localized blood collection will get better over 2 months.
A hanging salivary gland (a.k.a. submandibular gland) feels commonly similar to a large but soft grape. Your surgeon has the benefit of knowing what he has done surgically and how your progressed during your recovery.

He would also initiate the correct referral if your surgeon would be concerned about a malignancy.

I agree with your doctor.  RELAX.  The chances of cancer are extraordinarily remote and the risks of waiting for improvement are analogous to the likelihood of being struck by lightning.  Give yourself a few more months to hea.l Only if it persists at its current size at 6 months should you consider further tests, in my opinion.