Is my rapid waist expansion 6 months after lipo to abs/thigh lift a reason to worry? (Photo)

You need to follow up with your surgeon and get an assessment.
I do not recommend anybody travel long distances for elective surgical procedures especially not to developing countries.
Your doctor is responsible for the outcome of the procedure and you are responsible for choosing that doctor.
If you want a proper second opinion consultation then schedule that as an in person consultation with a local board-certified plastic surgeon. For second opinion consultations patients should come prepared with proper before and after pictures as well as a copy of your operative report. In the United States those can be requested from your surgeons office. Most likely your operative report will be written in Spanish but I would imagine that they will send you a copy if you requested.
Best,
Mats Hagstrom MD

Hi and welcome to our forum!A 6 " increase in waist circumference over a period of several weeks 6 months after liposuction is quite significant. I cannot determine the cause of this phenomenon from your photos. Postoperative swelling will increase / decrease depending upon your position. It may take up to a year to resolve. I do not see redness to suggest an infection, bruising, or massive swelling to account for this increase. This is not a normal postoperative phenomenon, and as such, I recommend an evaluation / examination by a board certified plastic surgeon.Best wishes...