What could be the cause of this lump/knot above my belly button? Is this going to get better? (Photo)

Dear Texas61374,
I understand your concern. Based on your photos, this can be swelling, seroma, residual fat or something else. However, without a proper assessment it would be difficult to determine what is wrong. It is best that you visit your plastic surgeon for further assessment. Only after thorough examination you can get proper recommendations and advice.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

Hello
and thank you for the question. I would suggest you wait another couple of
months  to see if there is going to be any improvement. In general,
surface irregularities result from aggressive liposuction too close to skin
surface. You should stay in touch with your surgeon. If these persist despite
lymphatic massages and steroid injections, sometimes they can be improved by
revision liposuction (more like using the liposuction cannula to break down the
scar tissue) or at times fat grafting to depressed areas. Another
option is to inject Sculptra into see indented areas. You should speak
with your surgeon. Best,

The protruding bulge could be due to lax fascia.  If this knot is hard rather than soft, this is not likely the case.  More likely would be a permanent suture remnant, exuberant scar, or walled off fluid collection. Discuss treatment options or revisions with your PS six months post-op if the knot has not resolved.Kenneth Hughes, MD, ABPS Board Certified Plastic SurgeonLos Angeles, CA

Thank you for sharing your question and photograph.  Unfortunately without an in-person examination of your tissues it is difficult to offer definite advice.  This may be swelling or a small fluid collection (seroma/hematoma) which will likely go on to heal with additional time.  That said irregularities from liposuction and any muscle laxity is most likely to only worsen as swelling resolves further.  Talk to your surgeon once fully healed about possible treatment options.

You appear to have some excess skin and/or fat that was not addressed with just a mini tummy tuck. A mini tuck does not remove excess skin or fat above the belly button, nor is the muscle tighten above the belly button.