Why does my body keep on rejecting my chin implant? (Photos)

My surgeon is even puzzled about this... Why is my body keep on rejecting chin implant? 1st implant done in March 28 2018. Removed in April 30 after the implant became exposed. Re-implanted in August 18 then removed again in September 28 after it tried to get out of my chin. This time my surgeon mentioned that he anchored it to avoid movement. However, just last night, I noticed a lump under my chin as if the implant is again trying to escape. Why is that and what do I do since this procedure really improved my appearance?